How often should I shock my pool?


How often should I shock my pool ?


The simple answer is “Whenever it needs it.” The real question is “How do I know when my pool needs a shock treatment ?”


First, it helps to understand what a shock treatment is and why we need to do it.

When clients (both canine and human) enter the pool, they introduce organics into the water. These include sweat, saliva, skin cells, body lotions, deodorants, soil, urine, loam, and a host of other things. Mother nature also contributes by blowing leaves and other debris into outdoor pools. These organics provide a food source for bacteria to live on. Although there are both good and bad bacteria, the health department generally insists that we get rid of ALL of them.

So we add sanitizers to the pool. When you use chlorine, ozone, or bromine, these compounds actually do two things: 1) they kill the bacteria, and 2) they break down the contaminants, helping to remove them from the water so they no longer provide a smorgasbord for new bacteria.

This is accomplished by oxidation – an oxygen molecule “attacks” the contaminants. You may have heard of oxidation in relation to a rusty old car, and it’s exactly the same thing. Just as oxidation can turn metal into dust, it will also break down the organics in the pool water.

Killing bacteria is fairly quick and easy, but dissolving the contaminants takes a bit more time and muscle. The problem comes when the sanitizer “falls behind.” If there is a choice between a live bacterium and the organic food source, the oxygen molecule will tend to attach to the food rather than the bacterium. So your sanitizer ends up working on the less important task. Unfortunately, while the sanitizer is working on the contaminant, the bacteria can multiply and you can end up with a bacteria “bloom.” If your water is cloudy before a shock treatment, but clears up afterwards, this is probably what is happening.

You could avoid shock treatments almost entirely by increasing the level of an oxidizing sanitizer so that it never falls behind. This makes sense if contaminants are coming into the pool at a fairly steady rate, but it is wasteful if the problem is just the occasional exceptionally dirty dog. In addition, some sanitizers (particularly minerals and UV) don’t use oxidation at all, so they are of no use in removing organics.

The purpose of a shock treatment, then, is to remove the organics and other contaminants from the pool. It is NOT intended as a replacement for sanitation, but it will help sanitizers be more effective.


If you are chlorinating a pool, it’s quite easy to measure when a shock treatment is needed. Your test kit should include tests for both free and total chlorine. The free chlorine is what is available for killing the bacteria. The total chlorine is the combination of free chlorine plus what has already been “spent” for dissolving organics. When the level of total chlorine exceeds the amount of free (usually by 2 ppm or more), then you know that you are falling behind and need to shock.

We’ve all walked into a public pool and been knocked over by the chlorine smell. It might surprise you to learn that this was probably the result of NOT ENOUGH chlorine, rather than too much! The level of organics has gotten out of hand, and what you smell is the byproduct – a combination of chlorine and ammonia, or chloramines. A shock treatment is needed to deal with the organics, followed by an increase in chlorine on a daily basis to prevent the buildup in the future.

No matter what sanitizer you are using you can certainly schedule regular shock treatments, but there is no single formula to determine how often. In general, if your water is getting cloudy before the treatment and clearing up afterward, then you need to shorten the cycle and/or increase your daily dose of an oxidizing sanitizer. The smaller your pool, the more often you will need to shock. An 800 gallon spa may require daily shock treatments.

You may also want to shock:

  • After exceptionally heavy use.
  • After a heavy rain or a windstorm that blows debris into the pool.
  • After a water change.

This last one may surprise you – you’d think that the water coming from your tap is clean and pure. It probably IS safe from live bacteria, but there may still be organics. I always shock after a water change.


There are two main categories of shock treatment: chlorine and non-chlorine. The former is simply raising the chlorine to a very high level – typically around 10 ppm. This provides enough oxidation to dissolve the organics AND rid the pool of bacteria that may have been busy multiplying during the imbalance.

The trouble with chlorinated shocks is that you cannot use the pool until the chlorine level drops back to normal levels – around 3 ppm. This can take some time, and you must test the pool water to ensure the level has dropped. In addition, if you are using an alternative sanitizer, it may not be compatible with the chlorine shock treatment.

Non-chlorine treatments generally use potassium monopersulfate. This will NOT kill bacteria, but it is very effective at oxidizing the contaminants. The labels claim you can swim 15 minutes after treating, although I still prefer to wait overnight.


  • You should leave the cover off the pool during a shock treatment. This is because nitrogen gas is expelled as a by-product, and you want to let it escape.
  • If you use a flocculant (a blue clarifier), add it after the shock treatment has had time to work.
  • You’ll probably need to vacuum the pool afterwards, since the oxidized materials will tend to sink to the bottom of the pool.
  • Certain sanitizers may reduce or eliminate the need for shock treatments, but shock treatments do NOT replace sanitizers.

Got questions about water quality, chemistry, or equipment?
Email Karen Hunter at:

The ACWT Pool GuruThe ACWT Pool Guru:
Karen Hunter
22609 102nd Ave SE
Woodinville, WA 98077
425 487-3078

Ozone Sanitation


I’m thinking about using ozone to sanitize my pool. What should I know?


Good choice! Ozone is an excellent sanitizer that is economical, environmentally friendly, and pleasant for our clients.

Let’s start with a basic understanding about how ozone works. You may be surprised to hear that ozone, chlorine, bromine, and peroxide all work essentially the same way – by oxidation. All these sanitizers are common chemical compounds that have an “extra” oxygen molecule. The formula for oxygen gas is O2, while ozone is O3. Plain old salt (sodium chloride) is NaCl, while liquid chlorine (sodium hypochlorite) is NaClO. Water, or H 2 O, becomes hydrogen peroxide, or H 2 O 2, with an extra oxygen molecule.

These compounds are “volatile” – that is, the extra oxygen molecule makes them unbalanced, and they want to return to the simpler compound. Happily, the extra oxygen molecule is attracted to oxygen-hating bacteria ! So when the two meet, the oxygen molecule detaches from the sanitizer and attaches itself to the bacterium. The bacteria die, and the ozone turns back into oxygen.

Okay – enough about chemistry. Lets talk about your options for adding ozone to your pool.

Because of its extreme volatility, plus the fact that it is a gas, you can’t just buy ozone and add it to the water. Instead, you must purchase an ozone “generator”, which makes ozone using the oxygen in the air or water. There are two common types of generators: UV light and Corona Discharge (or CD).

In my opinion, you should not even consider a UV generator for a pool, especially one that meets the needs of our furry clients. To generate ozone using UV requires that 1) the water be in contact with the lights for an extended period of time, and 2) there is no “interference” between the UV source and the water. In other words, you have to have a low flow system, you need to have a fairly large chamber with multiple lights, you need to keep the bulbs spotlessly clean, and any kind of cloudiness in the water will interfere with ozone production. In addition, the lights lose effectiveness over time, even before they burn out. In general, UV ozone generators are okay for sanitizing the drinking water in your motor home, but not much else.

CD models are capable of much higher ozone output, AND at a lower operating cost (less electricity, no bulb replacement). They are compatible with higher flow rates and aren’t affected by cloudy water. Most ozone generators sold for the pool industry are CD models, but be sure you ask. In a CD ozone generator, room air is filtered and bubbled into the water, which is then passed through electrically charged plates. The electrical charge adds the extra oxygen molecule, and the oxygen in the air is converted to ozone. A similar thing happens during thunder storms, which is why you often smell ozone after a lightning strike.

Hooking up an ozone generator to your pool is fairly straightforward. You’ll need to have a small bypass manifold between the filter and heater. Part of the water that is circulating will be diverted into the ozone generator.

Now here’s another thing you need to know about ozone and all the other sanitizers as well – in addition to being volatile, they are also corrosive ! Ozone will bleach out color just as chlorine and peroxide will. There can be other reactions: ozone has a tendency to break down silicone, polycarbonates (certain plastics) react to bromine, chlorine destroys latex, etc.

Proper dilution of these sanitizers in water helps to minimize these corrosive effects. However, since it’s a gas, ozone is a bit harder to dilute than the others. If you send the ozone gas directly to your pool, you are going to see immediate and serious damage to your pool cover! For this reason, along with your ozone generator, you want to be sure to include a degassing unit, also called an ozone tower.

An ozone tower is basically a tall pipe with an outlet at the top for gas and at the bottom for sanitized water. The water and the ozone mix in the pipe and the bacteria are killed. The gas bubbles (oxygen and unused ozone) are sent out the top (which should be vented to the outdoors), and the sanitized water, minus bubbles, is returned to your pool (not to the heater).

You can purchase ozone towers from most of the manufacturers of ozone generators, and you can also find them at aquarium stores. There are also build-it-yourself instructions for them on the internet. In my opinion, the taller the tower the better.

However wonderful ozone is, it is not usually sufficient as your only sanitizer. Ozone isn’t effective against algae. It doesn’t remain in the water, so you’ll still need a residual sanitizer such as chlorine, bromine, or copper. However, you’ll be able to use much lower amounts of the other sanitizers and still keep the water clean and healthy.

Got questions about water quality, chemistry, or equipment?
Email Karen Hunter at:

The ACWT Pool GuruThe ACWT Pool Guru:
Karen Hunter
22609 102nd Ave SE
Woodinville, WA 98077
425 487-3078

What is pH?


What is pH? Mine is frequently off, but my water looks fine.


Well, pH stands for “potential of hydrogen”, but I prefer to think of it as Potential Hazard. It is probably the single most important test in your pool kit, and keeping the pH in the correct range is one of the most valuable things you can do to keep your pool clean and safe.

pH is basically a measure of the relative acidity / alkalinity of a substance. It ranges from 0 (most acidic) to 14 (most alkaline), with 7 being neutral. Your blood, skin, saliva, and the diet Coke you drink all have pH values. When the pH in your body falls outside a certain range, it’s a sign that something is wrong. The same is true of your pool water.

The pH in your pool should generally be kept in the 7.2 to 7.8 range, although I shoot for between 7.4 and 7.6. If it gets outside this range, several things can happen.

The first is that your clients will be uncomfortable. Stinging, red eyes and itchy skin are symptoms of an undesirable pH. High pH levels also increase the likelihood of yeast infections – bad for dogs and people alike.

The second problem is sanitation. Chlorine and bromine do not work when the pH is too far out of balance. So you could be putting in chemicals to clean the water that are having little or no effect.

Finally, a pH that is too high can contribute to cloudiness in the water, while one that is too low can damage your pool and equipment.

A low pH can be raised with the addition of sodium bicarbonate – simple baking soda. Save yourself some money – instead of purchasing “pH Up” from the pool store, go to Costco and get a big bag of baking soda.

When the pH is too high, you must add acid to the water. Many people are reluctant to do this, believing that acid is a “bad” thing. Believe me, if your pH is too high, acid is a very good thing. It does require careful handling, though.

Changes in pH are easiest when they are small. Don’t wait until the pH is at the outside of the range to fix it. Once the pH is balanced and stable, testing two or three times a week (and making necessary adjustments) is probably all that will be needed. When you first set up the pool, after water changes, or after any major event (such as exceptionally heavy use or changing equipment), you should test and adjust daily until things stabilize.

If you are testing for multiple things (and you should be), and need to fix more than one, fix the pH first.

Final note: Many kits include a test for TA (Total Alkalinity). In general, having the TA in the right range will help stabilize the pH. However, changing one will change the other, and depending on other factors, it may be impossible to make both of them fall in the suggested range (this is not uncommon when using ozone, which tends to raise pH without a corresponding change in TA). When this happens, ignore the TA and focus on the pH. If your pH is in the right range and your water is not cloudy, TA is of little importance.

Got questions about water quality, chemistry, or equipment?
Email Karen Hunter at:

The ACWT Pool GuruThe ACWT Pool Guru:
Karen Hunter
22609 102nd Ave SE
Woodinville, WA 98077
425 487-3078

To build a Pool vs a Treadmill?


Hi! I am wondering why there are not more pools for hydrotherapy here in Australia yet? I have been researching the water treadmills and believe they would be an excellent rehab process amongst other types of medical reasons. Do you recommend them as an alternative if you do not have the room for a full functioning pool set up?

Thank you, Cathy

Answer (by Cindy Horsfall):

Hello Cathy,

This is a great question.

To build a POOL vs a TREADMILL….
Many things to consider here…

First, it’s important to consider the intent of your investment. After you have considered this,- you’ll want to explore the local laws to make sure you can legally do what you are intending.

If you get a treadmill, your goal would most likely be for rehabilitation work, gait re-patterning and strength building. In many parts of the world, there are laws against anyone but a licensed veterinarian to do any kind of rehabilitation work. Many in the USA have been shut down who have treadmills as its hard to say you are doing anything ELSE except rehab with a treadmill. Not so with a pool as you can change your wording to swimming and resistance work in water and stay away from the more clinical (and illegal) terms used with treadmills.

So the first thing I advise is for you to check your local laws and build a vision that complies with the laws.

Second, you brought up space as an issue… and yes, a treadmill can be carried in through a smaller door, you don’t need the headroom as your work is done at ground level and takes up half the space as a swim spa.

A smaller swim spa still takes up about 8×14 or more in floor space … with 3′ around it you’re looking at needing to dedicate a space at least 14×20. More than this, you do need a larger door or window so that the spa can be carried into the space and ideally you would have at least 10′ ceilings so you could build a ramp up and deck around it for safe access.

Expenses? A treadmill usually runs twice the cost of a swim spa as it’s a highly specialized item. Most likely, the expenses to run the treadmill are less however…

Both are excellent options and rewarding things to offer in your business. Please keep us posted on what you decide to do and good luck!!!! Let me know if you have any other questions or thoughts – – – –

What should I do about ventilation?


Hi: I am putting in a pool soon and am struggling with what to do regarding ventilation. What kind of systems/brand names of ventilation systems have been used to control moisture?

Thanks in advance, Ann Marie

Answer (by Sandy Fisher):

Hi Ann Marie,

I, personally, have a system put in by MM Comfort Systems (they are located in Redmond, WA). It is a full heating/dehumidification system. It works perfectly but was very pricey. Some people choose to just use an exhaust fan. Those are the only two options I have heard being used.

A lot of your needs will depend on your building and your pool area. Is the building heated? What are the materials the building is made of? Are the materials susceptible to damage from the humidity. It is very easy to have mold and mildew problems if humidity is not controlled. Do you have a lease or own the building? If you have a lease, you could be liable for all damages to the building from humidity so you will want to proceed with caution. Talk to the landlord and make sure you do whatever needs to be done to protect yourself. When I was looking t leased space, they required the walls to be painted with special paint and a dehumidification system to be installed (that wouldn’t be allowed to leave when the lease expired).

There is currently a discussion on dehumidifiers on the Yahoo discussion group. If you are not yet a member, you may wish to join that group. Here is the discussion:

Original Post:

Hi, Anyone out there tried or researched using a self standing de-humidifier to help with the moisture in your building or room? They have them that suck up 32 pints or more in a 24 hour period. Is this enough?

Response #1: A lot of it will depend on if you are heating the building (and to what temperature) when the weather turns cold. The colder the air, the more condensation you have, the more humidity you will have. Also, the surface area of the pool, how long the pool will be uncovered and what kind of cover you have will make a difference. What kind of building do you have and how tolerant of wet conditions is it? Can you use the dehumidifier in wet locations? Sounds silly since it is taking humidity out of the air, but they aren’t all necessarily made to be used around a pool.

Here’s a link to some dehumidifiers that can be used in pool areas:

The ones that handle indoor pool areas talk about taking care of 200 pounds of water a day (not pints). They start around $2,000. I would try and find out how noisy they are (not sure if they are like heaters where they make a lot of noise or not). Maybe call the company and see what they would recommend for your particular situation.

We have a full dehumidification system and are extremely happy with it. Our system is set to heat the air (and pool) as well as take the humidity out. A great system. However, very pricey but it is an investment. If you try shortcuts and have mold and mildew or the building gets damaged because the humidity couldn’t be controlled, you will end up spending more money in the long run. I’m amazed at how often our system is running even in the summer when it’s hot outside.

Response #2: I think that is about the size of my dehumidifier, and I don’t have a problem with it. I don’t even use it in the summer, I just have fans on and keep the windows open. I also have my pool covered when not in use, I will even put the covers back on if there is more than an hour between appointments. That really cuts down on the humidity. In the winter I have more of a problem, of course. It does get humid during the day, but I always have the windows open at least a little bit. At night I put several fans on and keep the dehumidifier running. I usually empty it before I go to bed and then as soon as I get up in the morning. If you can run a drain to the outside so the container doesn’t fill up, that would be preferable. It is an option for mine, I just haven’t done it yet! If you are trying to use the pool for heat and have it uncovered all the time, this size would definitely not work.

Which pool will be most tolerant of dog hair?


I am looking into starting a k9 swiiming pool. I need recommendations on which pools will be most tolerant of the hair.

Thanks,- Jennifer G.

Answer (by Cindy Horsfall):

Hi Jennifer! You can read the following topic on the ACWT website: What kind of pool or spa should I get?

When choosing a pool, the filter and circulation system will be very important. It’s best to work with the pool contractor or manufacturer of the spa/pool to set up a system that will be able to handle large amounts of hair. Filter and pump sizes are all dependent on the pool or spa size you select.

Pools and swim spas are usually built for people and pool maintenance companies always talk about hair nets and such… so most pool contractors and companies aren’t comfortable with HAIR… let alone DOG HAIR… so this is where you need to ask for them to think outside the box. You need to beef up any circulation system to push that hair through the filters. You should pay attention to the hair catch pots in your pool and can even ask for more or bigger catch pots which are designed to catch the hair BEFORE it goes to the filters. Some like the cartridge filters for hair as you don’t have to clean them but just toss them away and put in another one, while sand and DE filters you have to clean and backwash.

Hope this helps!

What kind of pool or spa should I get?


Hi, I am in the process of building a boarding and training kennel, and water therapy facility. We are starting with a covered outdoor pool and a pond. Because we’re located in the southeast the pond will be used primarily for sports and conditioning 3/4 of the year because of moderate weather. The pool though, there are so many choices it’s mind-boggling. Cost-wise, we are shooting for a rectangular 12′ to 16′ by 20′ to 32′ pool. Warm enough for therapeutic value, but cool enough for conditioning, too.

What are the pros and cons of pool types in the opinions of people already using the pools? Does the ACWT have a site or information we could rely on to make an informed decision?

We do plan to join ACWT once we’re open.

Thank you, Paula P.

Answer (by Cindy Horsfall):

Hello Paula! Sounds like you have a great business idea and we all can’t wait to hear about your new facility.

Since you have the luxury of having a pond for recreational swimming, what I would probably recommend is buying a swim spa for your therapeutic use. One option is the FLORIDA NORTH Swim Spa. Florida North offers a discount to ACWT members – check out our Membership page. Their Swim Spa is an 8′ x 20′ fiberglass portable unit. The spa itself retails for $11,500 (not including shipping and installation costs) and the bench and stairs are quite usable for therapy. Some of the swim spas we have seen have weird molded seats or little corner steps making them impractical for our canine friends. The Florida North spa is a stand-alone unit so it can be installed above-ground. There are also other options in swim spas such as the stainless steel and tile swim spa available from Bradford Products. However, these types of spas are over $30,000 (not including shipping and installation) and are much heavier than the fiberglass models which make installation a bit more limiting. For fiberglass or acrylic vessels, if you go with any size over 8 feet wide, you will probably need to install them in-ground due to weight and the pool’s inability to contain itself when full. Always check with the manufacturer to see what kind of installation is appropriate.

These are the reasons why I would suggest you consider a swim spa:

  • The swim jets and the circulation jets are strong, allowing for the water to turn over many times which leads to the sanitation that is always a challenge with dog hair. You don’t want a stagnant pool and those that do go with the in-ground pool have to beef up their circulation system to drive the pool water through the filters (3 options – DE/SAND/CARTRIDGE).
  • Swim spas can be portable and relatively inexpensive, allowing one to get into business on a limited budget with a great pool.
  • I have never had a dog who I couldn’t do wonderful therapy work in an 8′ x 20′ spa. Even 240 pound mastiffs have ample room for therapeutic swimming and work.
  • They aren’t too big so you can’t implement a complete dump/clean and water change with your program. This is an ideal situation for a canine spa. One rarely dumps an in-ground pool.
  • You can turn temperatures up and down as needed. Due to the lower water capacity over a pool, a swim spa is very efficient. I used to have tropical Tuesdays set at 96 degrees for the greyhounds and whippets and very elderly who only came in for massage and then it would be 88 degrees by Friday for the hard core swimmers. My usual temperature is 94 degrees for all kinds of work and my comfort. Also, maintenance costs are much less with a spa with lower water capacity.

Keep us posted here at the ACWT and good luck !!!

All About Filters

A properly maintained pool incorporates both filtration and sanitation. We sanitize to kill bacteria, viruses, and algae, and we filter to remove particles suspended in the water. While clear water is not a guarantee that the water is safe to swim in, cloudy water is definitely a sign that something needs attention.

Your filter is a critical part of your pool system, and should be selected with care and properly maintained. In this issue, we’ll provide some information to help you understand the various options and advantages and disadvantages of each.


Cartridge filters are usually what you will get with pre-packaged pools or spas. They work by trapping particles in a pleated, non-woven fabric. Cartridge filters are readily available and easy to operate. They occupy very little space and do not require a backwash outlet. However, they are less than ideal for a dog pool.

The cartridges require frequent cleaning or replacement. Cleaning usually involves a hose, lots of water, and a fair bit of time. An automated cartridge cleaner such as the Blaster ( is a good investment. It’s also a good idea to have extra cartridges available: one in the filter, one being cleaned, and one ready to go.

Cartridges are my least favorite choice. The amount of hair and dirt that dogs bring in causes them to clog quickly – you may be changing/cleaning them daily. They can remove particles from about 30 to 100 microns in size. This is the least effective of all filtering options, so you will not have optimal water clarity.

If you do use cartridges, try to choose something with as much square footage as possible (I’d recommend at least 200). The more square footage you have, the less often you’ll have to clean or replace cartridges.


Sand filters, which use several cubic feet of sand as a filter medium, have much lower maintenance requirements than cartridges. Their effectiveness actually improves as particles accumulate (up to a point). Sand filters can go several weeks between cleanings, and they are the best filter for handling large amounts of hair. Sand filters will remove particles as small as 20 microns.

Sand filters are cleaned by backwashing, which involves running the pool water backwards through the sand and out as waste. Very little or no sand is lost in the process. Backwashing also provides an opportunity to do a partial water change – a good practice no matter what type of filter you use.

Approximately every six months the sand should be washed with a special cleaning solution to remove oils that may accumulate. The sand itself should not require replacement for 4 years or more. A properly operating sand filter will NOT put sand into the pool.

Sand filters take up more space than cartridge canisters, and you must be able to run a waste hose from the filter to a drain or the outdoors.


Zeolite (sold under the brand name Zeobrite, is used in sand filters instead of “generic” sand. It is a natural, granular mineral similar in appearance to sand, but it has filtration abilities that are far superior. Zeolite can filter particles as small as 3 to 5 microns, which rivals DE. The cleaning and maintenance requirements are even better than sand – less backwashing is required, although you should still wash out the oils every six months.

Zeolite is also capable of boosting the effectiveness of you sanitation system because it can actually remove ammonia from the water.

A sand filter filled with Zeolite is my choice for filtration.

DE (Diatomaceous Earth)

Diatomaceous Earth is a fine white powder that looks similar to talcum powder. It is actually the skeletons of billions of tiny sea creatures. DE filters generally provide optimum water clarity, as they will filter down to 3 microns.

DE filters utilize a fabric covered grid. The DE powder is added to the water, usually by pouring it into the skimmer, and it then becomes trapped on the fabric.

DE filters require more maintenance than sand or zeolite. They require regular backwashing, but unlike sand, the DE powder is lost during the process and must be replaced. Most municipalities prohibit washing DE down the sanitary or sewer drains, as it will clog the filters in the treatment plants. You may have to add a recovery tank to meet building codes.

Because it is so fine, DE filters clog quickly. When clogged, they become “channeled”, meaning the water will bypass the DE and even though it is running through the canister it is not being filtered. Most DE filters have a “bump” function, which is like shaking the powder to redistribute it evenly.

DE filters should not be used with biguanide sanitizers such as Baquacil or SoftSwim, since they cause the powder to cake.

If you choose a DE filter, I recommend using it as a secondary filter after a cartridge filter. This will keep the larger particles out of the DE grid, and reduce the need for backwashing or bumping.

How Big?

Well, that question will fill a whole issue, so we’ll cover that in a future Splash. In short, however, bigger is better when it comes to filters, so don’t scrimp here.

Happy Swimming!

Note from ACWT President Cindy Horsfall: I value and understand everything that Karen says here in her article on filters. She’s got great advice and knowledge. However, I feel compelled to say here that I do love my cartridge filter and I wouldn’t replace it. I have a 150 sq ft cartridge filter for my 8×20 swim spa and I hose it out every 2 weeks and replace it (they cost about $80) every month. They are the easiest solution for me and my lifestyle.

Got questions about water quality, chemistry, or equipment?
Email Karen Hunter at:

The ACWT Pool GuruThe ACWT Pool Guru:
Karen Hunter
22609 102nd Ave SE
Woodinville, WA 98077
425 487-3078

Test Your Pool Chemical IQ

Do you know what you are putting in your pool?

Chemicals are a necessary part of pool maintenance. As much as we would like to eliminate them, it just isn’t practical (or safe) to go without.

However, it is vitally important that you understand what is in the chemicals that you do use, and also when they should be used. Without that understanding, you may be adding many more things than you need to, or in some cases actually doing harm to your clients and/or your pool systems.

Here’s a quick true/false quiz to test your pool chemical IQ.

  • You should never use “plain” chlorine – instead, use dichlor or trichlor which are specifically made for pools.
  • You should add a flocculent (blue clarifier) once a week.
  • Stains on your pool are a sign of metals in the water.
  • You should shock your pool once a week.
  • If your water is crystal clear then it’s safe to swim in.



While it’s true that dichlor and trichlor are specifically formulated for pools, it isn’t true that you should always use them. Dichlor and trichlor combine chlorine with cyanuric acid, which acts as a stabilizer. Stabilizer is a must in outdoor pools because sunlight can cause chlorine to dissipate very quickly. However, very little (if any) is needed in indoor pools. Even more important is that chlorine is used up and must be replaced, whereas the stabilizer stays around. So every time you add the dichlor or trichlor to the pool, you’re adding more stabilizer that you probably don’t need. It will build up over time, and it can even reach the point where it interferes with the chlorine’s ability to work. Then things go haywire in a hurry! The only way to remove it is to drain and replace the water.

You can avoid this by not adding stabilizer if you don’t need it. Stabilizer can be purchased separately (it is usually sold as ‘conditioner’), and you can use it with plain chlorine (calcium hypochlorite). Test strips can be used to ensure the proper levels of both the chlorine and the stabilizer.

NOTE: Chlorine in any form should be handled carefully, and always follow directions on the packaging. Do not mix products.


Flocculants are often referred to as “blue clarifiers.” They are useful when you have cloudy water due to tiny particles that are so small they pass through your filter. The flocculent works by causing these smaller particles to stick together into larger ones. The larger particles can then be trapped in the filter or will fall to the bottom of the pool where they can be vacuumed up.

Flocculants are generally safe to use. They are basically inert polymers – not likely to cause a problem for swimmers or react with other chemicals in the pool. The problem with the statement is “once a week.” If you have adequate filtration and circulation, then adding a clarifier once every two or three weeks is probably sufficient. Don’t assume you need one just because you see cloudy water. After heavy use your water will probably be cloudy for a few hours until your filter has a chance to catch up. When the water is still cloudy after several hours, then a clarifier may be called for.

You need to know that too much flocculent can actually have a reverse effect – it can make your pool cloudier than it was before !

#3 Maybe TRUE, maybe FALSE

Stains on the side of your pool MIGHT be caused by metals. However, they might also be caused by algae or other organics.

It seems logical that a rust colored stain is a sign of iron in your water, so you might purchase a product designed to remove it. However, most metal removers add phosphates to the water, and algae LOVE phosphates. If your stain is actually algae, then using the metal remover will cause the algae to multiply rapidly, making things MUCH worse.

The key here is to determine what is really causing the problem before you try to treat it. First, try a little pH reducer on the stain by putting the powder in an old sock and placing it on the stain for a few minutes. The acid in the pH reducer will remove metal stains, but will have little or no effect on algae. Alternatively, try a little laundry bleach or pool chlorine, which should remove algae but won’t affect metal stains. Better yet – take a water sample to your pool store to be tested for metals.

Once you know the real cause of the problem you can use the proper treatment to correct it.


Yes, you should shock your pool. However, depending on your pool and the use it gets, you might need to shock every day, once a month, or never. There is no magic number to determine how often to shock.

Shocking is a way to remove organics from your water – body oils, perspiration, saliva, skin cells, and all the other goodies that are introduced into the pool when we climb in. If we fail to remove them, then our sanitizers can be rendered ineffective. How often you need to shock is affected by the swimmer load, pool size, and type and level of sanitizer.

To determine when to shock a chlorinated pool, simply measure the free chlorine and total chlorine. When the total is more than 1 ppm greater that the free, shocking is recommended. In a brominated pool, use shock when the bromine levels drop. Add the shock in small increments, since it will cause your bromine levels to rise quickly.


Water that looks good is only one indicator of a well maintained pool. Clear water could still be way off in pH, which would result in red eyes and skin irritation. Clear water could also have dangerously high levels of chlorine or bromine, excessive bacteria counts, or undesirable nitrates or ammonia.

On the other hand, perfectly safe water might appear cloudy due to small bubbles caused when air is introduced into the pipes, or suspended particles of inert materials.

Your eyes and nose are good starting points for measuring water quality, but they aren’t a guarantee. Water testing is critical. Test strips that measure the critical things (pH, sanitizer level) are inexpensive and easy to use.


Wouldn’t it be nice if we could just have a tablet that we added to the pool once a week that would keep the water clean, clear, and safe? Sadly, it doesn’t exist. What your pool needs is not only different from the pool down the street, it is also different from one day to the next. The best way to keep out of trouble is to be educated. A knowledgeable pool professional is worth their weight in gold. They will test your water (usually for free) and help you find a targeted solution.

In short: Test before you treat, and don’t treat for a problem you don’t have.

Happy swimming!

Got questions about water quality, chemistry, or equipment?
Email Karen Hunter at:

The ACWT Pool GuruThe ACWT Pool Guru:
Karen Hunter
22609 102nd Ave SE
Woodinville, WA 98077
425 487-3078

Is Fluoride Safe for You and your Dog?

By Linda Joy, MSW

For the last 60 years, we’ve been assured that the addition of fluoride to our public water supplies is a safe and effective means of reducing dental decay. But is it really safe and effective? Or does fluoride pose health risks not only for us, but for our dogs? Although health officials insist that fluoride is safe, the reality is that politics often trump science when public policy is made. Therefore, with fluoride, as with all toxic chemicals, it is wise to investigate as much as you can and decide for yourself. To begin, consider the following questions along with their often surprising answers:

What is the actual fluoride chemical added to our water?

Hydrofluorosilicic acid is the chemical put in the vast majority of U.S. water supplies. It is not pharmaceutical grade, it is removed from the pollution scrubbers of phosphate fertilizer plants and contains contaminants of lead, arsenic and radium. This toxic industrial waste – which would be costly for the fertilizer industry to dispose of properly – is sold to water districts and is more toxic than lead.

Are there any health risks from fluoride for people and pets?

While the public has been assured of its safety, in actuality, the Environmental Protection Agency (EPA) has acknowledged that no chronic health studies have been done on this fluoride chemical. In March of 2006, The National Research Council (NRC) completed a three year review of the peer-reviewed research on fluoride. Numerous adverse health risks were cited such as disruption of the nervous and endocrine systems (including the brain and thyroid), bone fractures, and joint pain. A recently published Harvard study concluded that there was a seven-fold risk in osteosarcoma, or bone cancer, among young boys after exposure to fluoridated water. This study may have implication for dogs, since osteosarcoma, or bone cancer, is the most common bone tumor diagnosed in dogs in the U.S.

Dogs have a significantly higher rate of osteosarcoma than humans. Researchers at Colorado State University recently conducted a large study on osteosarcoma and dogs. In their abstract they state that the osteosarcoma rate in dogs is 8 in 100,000, approximately 8 times greater than that in humans. Their findings haven’t yet been published, and their research will be the first epidemiological study of the effects of fluoride on dogs. More research on fluoride’s impact on dogs and cats needs to be conducted to rule out, or determine, adverse health effects.

Is bathing and swimming in fluoridated water harmful for us or our dogs?

Fluoride in highly acidic water does enter the skin, although it is unclear whether neutral acidity, typical of most tap water, can do the same thing. However, since some studies indicate that fluoride can be absorbed through the skin, more research needs to be done in this area.

Since people and their dogs drink various amounts of fluoridated water, and many foods contain fluoride, how can the fluoride dose be controlled?

Simply – it can’t! Water is usually fluoridated at 1 part per million (1 ppm) to provide 1 mg of fluoride per liter of water. However, dogs and their humans who drink more than the average amount of this water will ingest higher levels of fluoride and be more susceptible to its toxic effects. There is no way of controlling the dose, which means fluoridation contradicts sound pharmacological principles. It is medically irresponsible and unethical to administer to everyone – without informed consent – the same medication without first determining individual need.

In addition, the fluoride content in processed foods and beverages adds to the total fluoride intake in both humans and their companion animals. People ingest fluoride from many common cereals, sodas, juices, etc., and fluoride is found in pesticide residues as well. As a result of this overexposure, in 2005 the Centers for Disease Control reported that 32% of U.S. children now have some form of dental fluorosis (permanent scarring of the teeth) due to ingesting too much fluoride.

Research indicates that pet foods can contain high levels of fluoride; a low fluoride commercial dog food can contain 40-60 parts per million of fluoride and a high fluoride dog food can have 460 parts per million or more of fluoride! However, little systematic research has been done regarding the fluoride content of pet food. With potentially high levels of fluoride (sometimes called fluorine) consumed by dogs, is it possible – as in people – that symptoms of arthritis, spinal abnormalities, etc. in dogs could actually be skeletal fluorosis (over-accumulation of fluoride in the bone)? The stages of skeletal fluorosis range from joint pain, muscle weakness and changes in the pelvis and spinal column to osteoporosis and to a crippling condition of the joints and vertebrae. Unfortunately, veterinarians typically aren’t aware that the fluoride content in pet foods could be very high and potentially impacting a pet’s health.

Is fluoridation effective? Are there benefits which outweigh the risks?

There is now agreement among dental researchers that any benefit of fluoride in fighting tooth decay comes from direct application to teeth, not from ingestion. The “effectiveness” of fluoridation is more myth than science. Most European countries are not fluoridated, yet World Health Organization statistics show that European dental decay rates have gone down as much as those in the U.S. In addition, major U.S. cities such as Seattle, Chicago, Cincinnati and Boston have been fluoridating for decades, yet they all are reporting rampant tooth decay among children. Adequate dental care and a nutritious diet are critical in reducing tooth decay, and both are absent in the low-income populations of these cities.

What are some recent developments around this issue?

Dr. Hardy Limeback, one of the scientists on the prestigious panel of the National Research Council that reviewed fluoride’s toxicity, has said that their report is highly relevant to the policy of fluoridation. Dr. Limeback has stated, “the evidence that fluoridation is more harmful than beneficial is now overwhelming.”

On August 19, 2005, 11 U.S. EPA Unions, representing over 7000 professional employees, called for a nationwide moratorium on fluoridation and also a congressional investigation of this policy.

In June, 2005, scientists at the Environmental Working Group asked the National Institutes of Health to list fluoride in tap water as a carcinogen.

The Fluoride Deception , published by Christopher Bryson in 2004, exposes the sordid history of fluoridation. Bryson discusses how industry and the military worked behind the scenes to bury or alter studies indicating fluoride’s toxic effects.

In 2001, Dr. J. William Hirzy, Senior Vice-President, Headquarters Union, spoke to the US EPA on behalf of his union. He said, “In summary, we hold that fluoridation is an unreasonable risk. That is, the toxicity of fluoride is so great and the purported benefits associated with it are so small – if there are any at all – that requiring every man, woman and child in America to ingest it borders on criminal behavior on the part of governments.”

How can we and our pets avoid fluoride exposure?

First and foremost, avoid drinking fluoridated water! One way to do this is by removing fluoride from all drinking water and cooking water, using systems like reverse osmosis, ion-exchange, or distillation. Be aware that common charcoal filters do not remove fluoride. Another option is to buy bottled water (check the ingredients for fluoride!) for your family and pets.

If you have an infant, do not use fluoridated water to make formula since this would give the baby a very high dose of fluoride. Infant formula reconstituted with fluoridated water gives the baby 250 times more fluoride than occurs naturally in breast milk! Children under 3 should not be exposed to more than one glass of fluoridated water daily, although it is best to avoid fluoride altogether.

Your dogs and other pets also need to be protected from high fluoride levels in their food. If you feed your dog or cat commercial pet food, call the companies and ask for the fluoride content. (Unfortunately this is difficult to determine since companies usually don’t test for fluoride.) Try to avoid commercial pet food (or people food) that uses mechanically de-boned chicken since it contains high fluoride levels due to incorporated bone particles, in addition to other ingredients that contain fluoride.

What can we do to help bring about an end to this harmful policy of fluoridation?

The best thing you can do is educate yourself about fluoride and its risks and then share this information with others. The website with the most comprehensive information on fluoride is . The vast majority of people still believe the myth that fluoride is “safe and effective,” and by educating others you can help bring about much-needed change in this perception. Fluoride’s documented health risks make it imperative to invoke the Precautionary Principle, which in the case of fluoridation translates into: when in doubt, leave it out!

Epidemiology . 15(4):S83, July 2004, Water Fluoridation and Canine Osteosarcoma

Linda Joy belongs to WA Action for Safe Water (WASW). WASW educates the community on the current science regarding fluoride’s toxicity, health risks, and effectiveness. For information, contact her at,