Frequently Asked Questions

Answer: If you have a DPD test kit, you need simply multiply the test result by 2.25 to obtain the bromine equivalency. This works because bromine is over twice as dense as chlorine.

Answer: No; drop size, concentration and color variation will provide inaccurate results.

Answer: First off, balance your water, paying particular attention to pH. Secondly, check your filter system and clean if necessary. Adjust valving for optimum circulation and allow it to run 24 hours a day until the pool clears. Turn on automatic cleaners to help stir things up. Backwash as necessary.

For suspended green algae, shock the pool...hard. Put in as much hypochlorite as it takes to turn the pool a cloudy, bluish/gray color. Brush the walls and floors towards the main drain. Backwash the filter when the pressure gauge indicates the need. Using a flocculent may be a good choice if the pool is extremely "swampy". If you cannot see the bottom of the pool, and it is filled with leaves and debris, it may be wise to drain the pool, acid wash and refill it.

After the chlorine level has come down below 5 ppm, add an algaecide and brush the pool again. When it all settles, vacuum the pool (to waste, if possible). Check and rebalance the pool water if necessary.

For algae which is not suspended, but only clinging to the walls, follow the same advice above, first shock with brushing, then add an algaecide, brush again, vacuum to waste (preferred) or vacuum and then backwash the filter. Use of a steel bristled brush is recommended for algae on plaster pools (use nylon brushes on vinyl). Filter, Filter, Filter.

For black algae, the brushing part is very important. You must tear through the protective layers so the chemicals can destroy the plant from the inside out. Pumice stones work well to knock off the heads of black algae. (Don't forget to vacuum them up later, and backwash them out of the filter ASAP). Also effective on the black algae nodules is sprinkling granular trichlor over the spots (of course if they're on the wall this is next to impossible). Rubbing the spots on the walls with a trichlor tablet or stick can also be effective to knock off the heads and get trichlor directly to the roots. Follow up with a dose of copper algaecide, or high strength polymers. Simazine, an herbicide, was a very effective black algae treatment, but is no longer available in America.

If algae has been an ongoing problem in your pool for several years, you may do well to drain the pool. Many years of algae builds up dead algae cells and lots of other solids in the water that contribute to its rejuvenation. Acid washing and/or pressure washing is preferable once drained, to kill the roots of the algae embedded in the plaster. NEXT: change the sand if you have a sand filter or change the cartridge if it is a cartridge type. Sand should be changed every 5-7 yrs (or every 2 if you use baquacil), and cartridge filters should have new elements every 1-2 years. If you have a DE filter (good for you!), you should remove the elements, spray clean, soak in a 10:1 water/bleach solution, rinse and replace. A well functioning filter will prevent algae.

Another item to look at is the method of sanitation and the type of filtering you have. Far too many pools out there were sold with marginal filter systems, meant to run 24 hrs per day. Well, these systems get old and tired, or the new owners only run it 12 hrs per day (or less). For good algae prevention, we need a combination of good filtration, sanitation and circulation. It may be time to consider changing the old pump and filter. It's cheaper and easier to pay a little up front for more chemicals, electricity or better equipment than all the money and aggravation spent on fighting algae blooms.

Answer: When chlorine is added to water, another dissociation occurs. When we add Cl2 (chlorine) + H2O (water), we get a reaction which leaves us with HOCl (hypochlorous acid) + HCl (hydrochloric acid). Hypochlorous acid is the active, killing form of chlorine. This is what does the real sanitizing work. The chlorine molecule or ion kills microorganisms by slashing through the cell walls and destroying the inner enzymes, structures and processes. When this occurs, the cell has been deactivated, or oxidized. The hypochlorous molecule continues this slash and burn until it combines with a nitrogen or ammonia compound, becoming a chloramine, or it is broken down into its component atoms, becoming de-activated itself.

Answer: Proper chemical balance and sanitizer residuals will prevent many opportunities for algae to bloom. high pH and low chlorine (or other sanitizer) can give algae a great start to genesis. General cleanliness of the pool is also important. Organic material and bacteria can contribute to algae growth. Regular brushing of seemingly clean pools is not only good exercise for you, but prevents dirt from harboring in the pores of the plaster, which is a good start for an algae colony.

The use of specialty chemicals or algaecides is recommended to provide a back up to normal sanitation and filtration processes and is completely necessary for many pools. These chemicals are described below:

POTASSIUM TETRABORATE: This chemical, when added to the pool water in proper dosage, prevents algae from converting carbon dioxide into the fuel it needs for growth. Manufactured under the trade name Proteam Supreme. An extraordinary product.

CHITIN: Not an algaecide (meaning to kill algae) per se, but its properties might be called algaestatic (that is, to prevent algae growth). Chitin has the ability to coagulate and remove a wide variety of suspended materials and impurities form the water. This allows the sanitizer to more effectively kill contaminants unobstructed. It also improves the effectiveness of the filtration equipment. Sold under the trade name Sea-Klear, chitin can be a valuable weapon in your algae arsenal.

ALGAECIDES AND ALGAESTATS:

1. QUATERNARY AMMONIUM COMPOUNDS: A low grade type of algaecide, Quats, as they are called, will usually have "10" somewhere on the bottle, representing 10% active ingredient. Although available at a lower cost, quats tend to produce a small amount of surface foaming. They are most effective as an algaestat, that is, as a prevention, not a cure.

2. POLYMERS: Polymers are long, complicated chemical chains that behave in water both as an algaestat and an algaecide. They are available in percentage strength of 30-60%, are non foaming, and work well as general, all around algae treatments. Poly-Quats are a blended compound of polymer and quats.

3. COPPER BASED: Copper is a proven algaecide and algaestat. Available in varying non foaming strength of 3-10%. It works very well on all types of algae, but it has the drawback of staining white plaster surfaces a light blue/green color if it precipitates out of solution. Most copper based algaecides are chelated, which means that agents have been added to prevent this, such as Lo-Chlor Algaecide.

4. SILVER BASED: Silver has been shown to be an effective bacteriostat, which means that it works to prevent bacteria from reproducing. Non foaming and effective with pink algae. In high doses, reactions with sunlight can cause colloidal silver to deposit as black stains on white plaster. When using copper or silver algaecides, the use of a sequestering agent is recommended.

CHLORINE ENHANCERS:

These are not algaecides, but work to provide a synergistic boost to hypochlorites when added separately, but at the same time. Sold under trade names like Mustard Buster, Yellow-Out or Yellow Treat, it is most effective on, you guessed it, yellow algae. Since it is not an algaecide, the makers are not required to tell what it is made of, but we do know that it works quite well, in conjunction with a little brushing and vacuuming on your part.

Answer: Typically one season. Reagents lose their strength over time and can also be ruined by direct sunlight and temperature extremes. Replace your reagents annually.

Answer: We can't tell you how many tablets or how many pounds or gallons you'll need for your particular pool, but your test kit will. Each pool has its own chlorine demand, the amount of chlorine needed to destroy contaminants that are present. And each pool also has a different capacity, or gallonage.

Other factors, such as the water balance, and particularly pH, have an effect on how much chlorine you'll use. Most health departments will close down a public pool that does not have a minimum of 1.0 ppm of free chlorine available in the water during a health inspection. With a little experimentation, you'll be able to determine how many tablets, for instance, it takes to achieve a consistent minimum level of 1.0 ppm.

For example, test the water, then add three tablets into your feeder. Check the residual in 12-24 hours. If it's too low, add more; too high, remove some. Fairly soon you will develop an idea of your pool's particular chlorine demand, however, this will change during warmer months and periods of increased use, among other things. Chlorine is an expensive and corrosive compound, so make the attempt to avoid consistently overchlorinating the pool, which may also irritate your swimmers.

Answer: I should say everyday, but I realize that's a bit much for most people. Commercial pools are required to check chlorine levels every hour and record their findings in a log, however the "backyard lifeguards" should check their pH and chlorine levels at least 2-3 times a week. Chlorine should be fed continuously through a feeder device to maintain a consistent level. Total Alkalinity and Calcium Hardness levels tend to fluctuate less, so weekly testing should be O.K..

Answer: No doubt about it, chlorine certainly is a hazardous product, with some forms of it being more dangerous for the handler and the environment than other forms. Chlorine in a solution of water at levels found in swimming pools pose no danger for swimmers. Allergic reactions to chlorine are rare, however some individuals may experience skin irritation. Chloramines, sometimes found in poorly balanced water, are the cause of occasional red eyes when swimming. Extremely high levels of chlorine in the water could possibly release enough gas off of the surface in certain conditions to render breathing difficulties.

The main hazard is towards the person in charge of adding the chlorine to the pool. Use caution and always read the directions. Always use care when opening a container of chlorine. Breathing in chlorine gas can knock you right out, and could be fatal. Always wear protective handling gear such as eye protection and rubber gloves. If chlorine touches your skin, you should wash it off to prevent irritation. If chlorine splashes in the eye, irrigate with water and contact a physician straight away. The label on the chlorine container will also tell you never, never, never mix chlorine with any other chemical. You could produce something of a bomb or even napalm. This includes mixing two different types of chlorine, or chlorine and bromine. KABOOM! Dirt, debris or any foreign substance (algaecides, alkalis and acids, etc.) can cause spontaneous combustion when mixed with chlorine. FIRE! See our page on Chemical Safety for more info.

As for the environment; pools have a small impact. Being closed systems, pools just don't contact nature very much. There could be some hazard involved with waste water from the pool that has either extremely high chlorine levels or extremely low pH levels. It is unlikely that the amount of water expelled during backwashing your filter could pose much harm, but large amounts of DE Powder can choke a stream if pumped directly into it. Impacts have been seen on drain and clean jobs, when acid water is pumped into nearby streams. Pool water is very similar in make up to the city water right out of the tap. Many people water their lawns with higher chlorine and lower pH than is found in their pool. There are certain industrial uses of chlorine chemistry which are detrimental to the environment, but in a swimming pool environment, the potential hazards are much lower, even non-existent. There has been much publicity and controversy over chlorine in recent years, with some organizations calling for bans on its use. You decide if chlorine chemistry is right for you and your pool.

Answer: If chlorine levels are excessively high, the content can bleach out DPD, a reagent commonly used for chlorine testing. Either dilute the sample with chlorine free water, or double the # of drops of DPD, and multiply or divide accordingly. There has been evidence that excessively high levels of stabilizer, or cyanuric acid, can cause a phenomenon called chlorine lock. Levels above 100ppm of cyanuric acid (CYA) may prevent chlorine from registering and possibly sanitizing. Lower CYA levels by dilution.

If you smell chlorine in the water, you are very possibly aware of combined chlorine, known as chloramines. These will not register in a test for free chlorine. A good DPD test kit will allow you to test for total chlorine levels and free chlorine levels; the difference being the combined levels. If trace amounts of combined chlorine is above .3 ppm, you may need to shock the pool to break the bond of chloramines; this shock level is around 30 ppm.

Answer: Cyanuric acid is a chlorine stabilizer, providing a chemical cloak around the chlorine molecule which protects it from the sun's UV radiation, the largest killer of your chlorine. It can be a real money saver, that cyanuric, especially during the hottest times of the year. A test kit can measure how much cyanuric acid is present in the water. Recommended levels from the National Spa & Pool Institute are at 30-50 ppm. The stabilizer (also called conditioner) is fed directly into the skimmer at a rate of 4 lbs per 10,000 gallons. It dissolves inside the filter and you will immediately see a reduction in your chlorine demand. If you are using chlorine from the iso-cyanurate family, the cyanuric acid is already present in the tablet and you shouldn't need to add any additional, unless the level is below 30-50 ppm.

Answer: The efficacy of chlorine, that is, the power of it to have an effect, is greatly influenced by the care with which you manage your pH levels. As the pH of your pool increases, the killing power of your chlorine decreases. At a pH of 6.0, we'll get 96% or so of the potential out of each lb of chlorine, but at what cost? Such a low pH would wreck havoc on all of the surfaces the water comes in contact with, including swimmers. It's just too corrosive. Move the pH up to 7.0 and the efficacy of the chlorine drops to 73%, but raise it up to 8.0, where many a pool seems to drift to, and it drops dramatically...down to 21%! At a perfect pH level of 7.5, we can expect to have about 50% of our chlorine in the molecular structure of hypochlorous acid, the active, killing form. The remaining half is in the form of a hypochlorite ion, which is also an active form of chlorine, but very weak and slow to kill.

Answer:

pH: 7.2 - 7.8

Chlorine: 1.0 - 2.0 ppm

Total Alkalinity: 80 - 120 ppm

Calcium Hardness: 180 - 220 ppm, though some say 200 - 400.

Cyanuric Acid: 25 - 50 ppm

Total Dissolved Solids:: 500 - 5000 ppm

Answer: Algae spores constantly enter the pool, brought in by wind, rain or even contaminated swimsuits or equipment. When conditions are right, an algae bloom can occur seemingly overnight. These conditions include out of balance water, warm temperatures, sunlight and presence of nitrates and/or carbon dioxide. Of course, a lack of proper circulation, filtration and sanitation may be the primary cause of the algae. The best process is one of elimination.

Algae is a living aquatic creature that multiplies rapidly on warm, sunny days. Containing chlorophyll, algae utilize photosynthesis to grow. That is, they take in carbon dioxide and expend oxygen as a byproduct.

Answer: Ah, the many hues of swimming pool water. A bit disconcerting when it happens, but at least there's a visual indication of a problem. Unless your friends are real practical jokers, we'll find the source of colored water to be either mineral or algae contamination.

Organic problems such as algae and bacteria can discolor the water and deposit themselves on pool surfaces in a rainbow of greens, blacks, yellows, pinks. Algae deposits are distinguished from stains in that they are on the surface and not impregnated into the plaster. A more detailed discussion of their genesis and eventual destruction is covered in the algae page. Other organic materials such as leaves, worms, or other vegetable  matter can also stain pool plaster. An organic stain can usually be removed by sprinkling granular chlorine over it. If it doesn't, its probably some other type of stain.

Inorganic materials like copper, iron, manganese, calcium or aluminum can also cloud or discolor the pool water and stain or scale the pool surfaces, especially the plaster and tile grout. When a precipitated metallic salt such as calcium or magnesium remains in suspension, it can cause turbidity or cloudiness of the water. When heavy metal minerals are in suspension, they'll color the water. When these minerals quit floating around and decide to attach themselves or deposit on interior pool surfaces, the mineral salts such as carbonates of magnesium and calcium form a whitish crystallized deposit known as scale. If the precipitated minerals have color, as heavy metals often do, they will deposit themselves in the form of a stain.

So, in summary, precipitated (which means to come out of solution) carbonates of metallic salts will cloud the water and / or form crystal deposits on surfaces, while heavy metals will discolor the water and / or deposit themselves as stains.

Minerals like iron, calcium and copper exist naturally in trace amounts in your pool water. They may originate from the source water, that is, the water used to fill the pool. Well water is notoriously high in mineral content. Not much we can do about minerals entering in this manner. Other means of entry are more controllable.     Iron and copper pipes, fittings and equipment found in older pools are subject to corrosion by harsh chemical conditions, such as high chlorine and low pH. They also erode slowly with the everyday force of water rushing through. This corrosion and erosion releases heavy metal ions into the pool, which may be forced out of solution (precipitated), creating dramatic color schemes when free floating and stains when they deposit themselves.

Another source of metal ions occurs when two dissimilar metals are placed in close proximity to each other. For example, iron pipe connected to copper pipe, or a brass valve connected to aluminum equipment. These metals will attempt to exchange ions; water rushing in between them prevents the exchange, carrying off bits of their essence to the pool. This is the principle behind ionization systems.

A frequent source of copper discoloration and staining is the heat exchanger in the heater. Water rushing through the 8 or 10 tube, copper finned heat exchanger, at possibly higher than normal flow because of an oversized pump or faulty bypass valve, or containing corrosive water with high chlorine levels and/or low pH, will strip the copper right out. Corrosion and scaling conditions are dramatically increased by the high temperature found in heaters. As heat exchangers erode, the pool becomes stained and the exchanger tube walls become thin and begin to leak. ($$$)

Finally, staining can occur with the less than proper use of ionization systems and metal based algaecides. Copper is a known algaestat, while silver ions are a good bactericide. Copper and silver ionizers inject these metals into the water for contaminant control, however, if the water balance is out of control, or mineral levels are too high, staining can occur. The same is true for the algaecides, although some are chelated, which means they have agents contained in them to prevent minerals from coming out of solution.

Preventing Mineral Problems

Balanced pool water is such that it has neither a tendency towards corrosion or scaling. At the most basic level, pool water must be balanced to control stains and scale. pH or alkalinity that is allowed to drift and/or high calcium hardness levels can promote mineral precipitation.
The use of a sequestering agent (also called chelators) is recommended for pools which have metal plumbing, fittings, heaters, ionizers or use metal algaecides or fill their pool with well water. These agents keep minerals tied up in solution like molecular glue.

Correcting Mineral Problems

For pools that are discolored or cloudy due to precipitated minerals, the path back to blue may be accomplished by:

Shock treatment with sodium or lithium hypochlorite, accompanied by constant filtration and use of a clarifier.

Use of a flocculent to drop suspended particles to the floor for vacuuming.

Partial drainage and dilution of the pool water, especially in cases where the pool is at or near saturation. When TDS levels are too high, the water can accommodate no more dissolved material and must throw off some of it in the form of precipitation. (This is similar to the Jr. High science experiment where sugar or salt is continuously added to a glass of water until saturation is reached and it won't dissolve any more).

Answer: The four main tests to perform with a test kit are pH, chlorine (or other sanitizer residual), Total Alkalinity and Calcium Hardness. Cyanuric Acid levels, mineral content, Total Dissolved Solids and Acid or Base Demand tests may also be performed as needed.

Answer: In its elemental state, chlorine exists as a gas. Gas is available for swimming pool sanitation; is very cheap, and is the purest form of chlorine, with no binders or carriers. The % of available chlorine is 100%. It is also extremely dangerous and restricted in its use. It is rare to find a pool using gas as it's sanitizer, and those that do are usually very old, very large public pools that have (we hope) enacted strict safety procedures. Gas is very acidic, with a pH close to muriatic acid, so these pools using it add a lot of base to counteract this.

Liquid chlorine is another type which is created by bubbling the chlorine gas through a solution of caustic soda. The yellow liquid (stronger, but chemically identical to bleach) has 10-15% available chlorine, and has a pH on the other end of the scale at 13. Liquid Chlorine is called Sodium Hypochlorite (NaOCl) and because it is already in solution, sodium hypo produces hypochlorous acid instantly when it contacts water. The liquid can be poured directly into the pool, but it is recommended to use a diaphragm or peristaltic pump. The use of liquid chlorine is more dominant in larger commercial pools which have it delivered into 55 gallon vats. For most residential pools, its lower cost seems to be outweighed by its difficulty in use and the amount of acid required to counteract its pH of 13. Use care when handling as this chemical is corrosive to just about everything.

Trichlor is a tablet form of chlorine, and is short for Trichloro-s-triazinetrione, a stabilized form of chlorine that has achieved a great amount of use in the last ten years. "Stabilized" means that it has cyanuric acid pressed into the tablet. Cyanuric, also called stabilizer or conditioner, is like sunscreen for the chlorine molecule; an extender, if you will. Trichlor is created by combining the salts of cyanuric acid and chlorine gas into a tablet or stick, and is 90% available chlorine. The pH is somewhat low at 3, so the pH in your pool may gravitate downward. This form is slow dissolving, and so it works well in floaters or in-line erosion feeders. Using tablets in the skimmer is not recommended, because of the corrosive nature of the chemical contacting metal pipes and equipment. This becomes more of a problem when the filter pump is operated on a timer. It has been known to strip out the copper inside of a heater. (An effective, yet expensive means of controlling algae). Tablets should also not be thrown directly into the pool, they can stain and etch plaster and bleach and deteriorate vinyl.

Another member of the chlorinated iso-cyanurate family is Dichlor, short for Sodium Dichloro -s-triazinetrione. Dichlor is made in roughly the same manner as trichlor, however the product is much different. The pH is a very acceptable 7, and it is manufactured in the form of granules, so it dissolves rapidly and goes right to work on contaminants. Dichlor has less chlorine, pound per pound at only 62% available chlorine. Because it contains cyanuric acid, it lasts longer than other unstabilized forms of granular chlorine. It can be used as a shock treatment oxidizer, or for normal sanitation. Dichlor's main drawback is it's cost per pound of available chlorine. It is perhaps the most expensive form of chlorine available.

There are two other types of granular chlorine on the market - the hypochlorites. Lithium Hypochlorite, like dichlor, is a very expensive product. At only 35% available, it takes almost 3 lbs of lithium to equal one lb of trichlor and its pH of 11 will require additions of an acid to adjust the pool water. It's main advantages are that it is calcium free, and so it won't contribute to hardness levels; it's dust free and non-flammable. It dissolves extremely quickly, before it hits the floor, so its use is safe in vinyl liner pools. Lithium can be used for either shock treating or for regular chlorination.

Calcium Hypochlorite is commonly available in is granular form, but can also be purchased in tablet form. Cal Hypo is a commonly used shock treatment throughout the country. Although not stabilized with cyanuric acid, it has a quick kill rate against algae and chloramines, and has 65% available chlorine per lb. Some other granular forms of chlorine are more powder like, and thus dissolve more rapidly than the larger granules of cal hypo. It's a good idea to pre dissolve cal hypo into a bucket of water prior to adding it to a pool. It's popularity is due mainly to its availability and low price, despite a high pH value of nearly 12, and the calcium binders used which contribute to higher hardness levels. Cal hypo is more dangerous and unstable than other forms in that it is very dusty and becomes contaminated easily by foreign substances which can cause combustion. Mix only with water, don't breathe the dust, and keep the lid tightly secure and clean.

Answer: If your reagents are in good condition, a purple color in a pH test is an indication of chlorine levels being too high and interfering with the test. Add a drop of thiosulfate reagent to remove the chlorine from a new sample, and test again.

Answer: These are synonymous terms for oxidizing everything in the pool. By raising chlorine levels ten times the level of chloramines, a threshold is reached called breakpoint chlorination. When this is reached, something of a shock, or perhaps more akin to a lightning bolt, rips through the water, slashing and burning everything in its path.

When to shock? Some recommend shocking the pool when combined chlorine levels reach .3 ppm, while others suggest shocking after a party full of kids get out of the pool :-) (the theory here is that kids=urine=nitrogen+chlorine=chloramines). Others recommend it once every few weeks, whether it needs it or not. You may use your senses to determine the need for shocking. If the pool is hazy, because somebody left the filter off or forgot to add chlorine, your eyes may tell you it's time to shock. If you notice a strong chlorine smell to the water, and the eyes are burning, you may sense the need for shocking. Large doses of chlorine, in the way of shocking, are also very effective when algae has turned the water or walls a yellow or green color.

How much chlorine is required to shock? Generally, we want to raise the chlorine level up to around 10 ppm. If using cal hypo, you'll find that at least one bag per 10,000 gallons will do the trick. A little more wouldn't hurt, because if you don't reach the crucial level of breakpoint chlorination, not only is the chloramine problem not solved, but matters have been made potentially worse. Follow instructions on the package of granular chlorine shock or non-chlorine shock, which may be potassium peroxymonosulfate. Liquid chlorine can also be used for superchlorination. Whatever chemical, we must introduce 10 times the potential of the chloramines. For example, if combined chlorine levels are at 1.0 ppm, we need 10 ppm of free chlorine levels to reach breakpoint.

Answer: These are states of existence for the chlorine molecule. If a molecule is free, it has not bonded with or combined with another compound. It is therefore available for sanitizing. When free chlorine molecules encounter and destroy a nitrogen or ammonia containing compound, they combine with them to create a combined chlorine compound, or a chloramine. The chloramine is no longer available to sanitize anything, and it floats around in the water, blocking the path of those do-gooder free chlorine molecules, and stinkin' the place up! If you smell a strong aroma of chlorine in and around a pool, chances are it has high combined chlorine levels. This level can also be tested with a DPD test kit which measures total and free levels separately and allows the tester to determine combined levels by subtracting the two. Total chlorine is simply the sum of combined and free levels.

Answer: Water balance is not such a complicated exercise. It is simply the relationships of different chemical parameters to each other. Your water is constantly changing. Anything and everything directly and indirectly affects water balance - from sunlight, wind and rain to the oil, dirt and cosmetics which may enter the water.

You will likely not change the water in your pool for many years. Continuous filtration and disinfection remove contaminants which keep the water enjoyable, but this is not water balance. A pool that is "balanced" has proper levels of pH, Total Alkalinity and Calcium Hardness. It may also be defined as water that is neither corrosive or scaling. This concept is derived from the fact that water will dissolve and "hold" minerals until it becomes saturated and cannot hold any more water in solution. When water is considerably less than saturated it is said to be in a corrosive or aggressive condition. When water is over saturated, and can no longer hold the minerals in solution; this is known as a scaling condition. So then, balanced water is that which is neither over or under saturated. The cliché that "water seeks its own level" certainly applies here. Water which is under saturated will attempt to saturate itself by dissolving everything in contact with it in order to build up its content. Water which is over saturated will attempt to throw off some of its content by precipitating minerals out of solution in the form of scale.

How do we know when our water is over or under saturated? First of all, we use a good test kit (with fresh testing reagents) to measure the chemical parameters of pH, alkalinity and calcium hardness.

pH:

pH is a measure of how acidic or basic the water is. pH is a logarithmic scale from 0-14, with 7 being neutral. Below 7, a substance is defined as being acidic, while levels above 7 are said to be basic or alkaline. Everything that enters your pool has a pH value. Heard of acid rain? This is rainfall with a very low pH. The human eye, at a pH value of 7.35, is just slightly basic. This is coincidentally, in range with proper pH levels for your pool. To have pH in balance, we adjust the water with additions of pH increasers (bases) or pH decreasers (acids) to achieve the range of 7.2 - 7.8. If your testing (recommended daily) of the water shows a pH value below 7.2, the water is in an corrosive (acidic) condition, and we need to add a base to bring the pH into a more basic range and prevent corrosion. Conversely, if the pH is above 7.8, we are in a scaling (basic) condition and must add an acid to bring down the pH to prevent the formation of scale.

Total Alkalinity:

A close cousin of pH, the level of alkalinity in the water is a measurement of all the carbonates, bicarbonates, hydroxides and other alkaline substances found in the pool water. pH is alkaline dependent; that is, alkalinity is defined as the ability of the water to resist changes in pH. Also known as the buffering capacity of the water, alkalinity keeps the pH from "bouncing" all over the place. Low alkalinity is raised by the addition of a base (just like pH); sodium bicarbonate is commonly used. High levels of alkalinity are lowered by the addition of an acid (again, just like pH). Experts recommend "pooling" the acid in a small area of low current for a greater effect on alkalinity. That is, adding an acid will lower both pH and alkalinity. Walking the acid around the pool, in a highly distributed manner is said to have a greater effect lowering the pH than the alkalinity. Pooling the acid has the opposite effect. A very important component of water balance, alkalinity should be maintained in the 80-120 ppm range. Levels should be tested weekly.

Calcium Hardness:

When we speak of scale, we are talking about Calcium Carbonate, which has come out of solution and deposited itself on surfaces. It is a combination of carbonate ions, a part of Total Alkalinity and Calcium, a part of the Calcium Hardness level. The test for Calcium Hardness is a measure of how hard or soft the water is. Hard water can have high levels of calcium and magnesium. If these levels are too high, the water becomes saturated and will throw off excess particles out of solution, which then seek to deposit themselves on almost any surface inside the pool. This is calcium carbonate scale, a whitish, crystallized rough spot. If the levels are too low, the water is under saturated. The water becomes aggressive as it attempts to obtain the calcium it needs. Such soft water will actually corrode surfaces inside the pool which contain calcium and other minerals to maintain its hardness demand. If your Calcium Hardness levels are too high, you can use TSP to lower the levels, or a product called Hydroquest. It can also be accomplished by dilution (adding water to the pool which has a lower calcium hardness content). Levels which are too low require the addition of calcium chloride. Recommended range for calcium hardness is 200 - 400 ppm. Levels should be tested weekly.

The Saturation Index:

Also called the Langelier Index, this chemical equation or formula is used to diagnose the water balance in the pool. The formula is SI = pH+TF+CF+AF-12.1. To calculate the Saturation Index, test the water for pH, temperature, calcium hardness and total alkalinity. Refer to a chart for assigned values for your temperature, hardness and alkalinity readings and add these to your pH value. Subtract 12.1, which is the constant value assigned to Total Dissolved Solids, and a resultant number will be produced. A result between -0.3 and +0.5 is said to indicate balanced water. Results outside of these parameters require adjustment to one or more chemical components to achieve balance. This formula is not foolproof, however. Some readings for pH, calcium and alkalinity which, taken individually would be considered to be well beyond recommendations, can combine within the formula to produce "balanced water", when it just ain't so. Regardless, the SI can be used to pinpoint potential water balance problems.

Answer: The first noticeable problem is that no one seems to want to go swimming. The second problem is that it requires work and effort and money to rid the water completely of algae. It is therefore best to use preventative chemicals and techniques, described later. Algae can cloud and color the water, making rescue attempts difficult and reducing depth perception of a diver. Algae itself is not harmful to swimmers, but pools with algae may also be harbor to pathogens like E-coli bacteria. In addition to clogging up sanitation pathways in the water, algae also clogs up the pores in a filter, decreasing filter effectiveness and requiring more backwashing or medium replacement. Algae creates a chlorine demand in the water for itself, actually consuming chlorine that should be working on other contaminants. Algae are kind of like weeds in your garden. Unsightly, unwanted space takers that create more work for the gardener, and sap up nutrients and resources from the flora we wish to grow.

Answer: There are many different types of test kits commercially available. If you are concerned about water balance, (and you should be) you will want to spend more for a nice kit. The basic "duo" test kits, available for about five bucks, are usually OTO chlorine and pH testers only. You may wish to spend more for a DPD chlorine kit, which measures free, combined and total chlorine levels (OTO measures only free levels). Also important is the ability to test total alkalinity and calcium hardness.Acid demand and base demand tests will allow you to perform a titration test on your pH sample. Simply count the # of drops to determine, with the help of a chart, exactly how much acid or base is needed to adjust the pH. A "four-way" test kit will test pH, chlorine, alkalinity and acid demand. Test strips are available now with "Litmus test" technology. These are "dip & read" strips of paper that turn colors indicating levels of pH, alkalinity and chlorine in the pool. Fairly simple to use, however, it seems that they may not be quite as accurate. Your pool professional can check the water for metal presence, cyanuric acid levels and TDS (total dissolved solids). If you have a biguanide water treatment system or a chlorine generator, you'll obtain special test kits from these dealers.

Answer: There are over 21,000 known varieties of algae! In the pool business we avoid all of the complication by referring to algae by the color they exhibit.

GREEN ALGAE:

An extremely common variety, green algae will usually rear its ugly head immediately following a hazy condition in the water from a lack of proper filtration and/or sanitation. It is frequently found free floating in the water, although it also will cling to the walls. It reduces water clarity and is thereby distinguished from severe copper precipitation, which will impart a clear, green color to the water. Varieties of green algae also appear as "spots" on surfaces, particularly rough areas, or places where circulation is low. They also show up as "sheets", where large wall sections, or even the entire pool, is coated in green slime...UGH!

YELLOW ALGAE:

A wall clinging variety, also called mustard algae, is usually found on the shady side of the pool. It is sheet forming, and can be difficult to eradicate completely. Once begun, a pool owner could spend the entire season fighting yellow algae; reinfection is common. This variety is resistant to normal chlorine levels and must be dealt with firmly. Hit it hard!

BLACK ALGAE:

Perhaps the most aggravating strain of algae, it has been compared to herpes; "once you've got it, it's there for life". This is not entirely accurate, but the difficulty in eradication is due to the strong roots and protective layers over top of the black algae plant. Black algae will appear as dark black or blue/green spots, usually the size of a pencil eraser tip. Their roots extend into the plaster or tile grout, and unless the roots are destroyed completely, a new head will grow back in the same place. The heads also contain protective layers to keep cell destroying chemicals from entering the organism. Like yellow algae, black strains can bloom even in the presence of normal sanitizing levels and proper filtration. I was once told that this form of algae commonly enters a pool inside the swimsuit of a person who's recently been to the ocean.

PINK ALGAE:

Not really an algae at all, but a form of bacteria. Appears as spots or streaks in corners and crevices. It is slow to spread and rare that it will bloom over an entire pool.

Answer: Suspended micro particulate matter, interfering with the passage of light is known as turbidity. It can range from an almost imperceptible haziness to a pure, milky white color. Besides being unattractive, cloudy water can prevent the rescue of swimmers in trouble and may provide no depth perception for those who would dive into the water. This particulate matter also interferes with the ability of the filter and chemicals to properly sanitize the water.

This particulate matter can be carbonates and sulfates forced out of solution by imbalanced water, perhaps worsened by the introduction of high temperatures. The situation could also be the result of poor filtration and sanitation programs. It can indicate a problem with the effectiveness of the filter or the amount of time its allowed to run each day or it may point to sanitizer residuals being too low or inconsistently applied. Finally, cloudy water may result from pool water which has reached saturation. High TDS levels may not permit any more solids from being dissolved or saturated into solution.

Use of clarifiers, or chitin products such as Sea-Klear work to coagulate smaller particles into larger, filterable clumps. Use of these products are a helpful boost to your sanitation and filtration program, and are especially necessary in pools with undersized or inefficient circulation/filtration systems.

For extremely cloudy pools, shocking with lithium or sodium hypochlorite, followed by constant filtration with the use of clarifiers may be the best solution to the problem. If not, you may want to drain some of the water and dilute with less saturated fill water and / or use a flocculent to settle suspended material to the bottom for vacuuming.

Answer: Several factors can contribute to foaming in pools:

• Soft water; low calcium hardness levels.
• High TDS levels. Lotions, oils and animal fats in the water.
• Poor water balance.
• Low grade algaecides. 10% polymers.
• Tile cleaning phosphates.
• Use of aeration (air jets) in biguanide treated pools.
• Practical jokers with a box of soap.

Correcting the above conditions can reduce or eliminate foaming.

Anti-foaming agents are available.

Chitin products like Sea-Klear can prevent or eliminate foaming from occurring. The Natural Chemistry line of enzyme products are also very effective anti-foam agents. Sometimes balancing the water and chocking the pool can remove the foaming.