Factors Of Water Conditioning

It is desirable and possible to maintain sparkling clear sanitary conditions in your pools water. To attain and maintain this optimum water condition, you must consider the three factors that make it possible; CHEMICAL, BIOLOGICAL and MECHANICAL. Pure water is a tasteless, odorless, colorless compound. If natural water were pure and contained no suspended or dissolved matter, and could be maintained in this condition, there would be no need to test, analyze and treat swimming pool water. However, all water contains some impurities, either in solution (invisible) or suspended (visible). Water testing detects these impurities while filtration, chemical balance and biological treatment controls them. Impurities in the water, whether entering the pool in the fill water, from the environment, wind blown atmospheric wastes, or swimmer waste are either dissolved in solution or suspended particulate impurities. Suspended particles can be organic or inorganic. They are visible (cloudy, fuzzy or dull appearing water) and should be removed by filtration. Dissolved impurities cannot be seen and are not removed by the filter without chemical aid. To assist the filter in removal of organic waste particles (Sunscreens, oils, hair sprays, cosmetics, dead skin, etc.) the chemical balance of the water must first be kept at an excepted level.

REMEMBER: It is not the water itself that has to be treated, but the various impurities in the water.

To maintain quality pool water, you have to relate water chemistry and disaffection to all three factors related to pool maintenance.

For example, if the pool filter is dirty or not working properly, or circulation is not getting all of the water to the filter, the water clarity will be poor and chlorine usage will be greatly increased. This situation can cause poor sanitation and increased chlorine consumption, which increases costs. This indicates that not only should you perform routine maintenance (backwashing or cleaning the cartridge), but also clean the internal filter media and look for possible filter or pump damage.


PH is a very significant factor and exerts the most influence on the scale formation or corrosives of your sanitizer (chlorine/bromine). The Ph of your pool water will determine the efficiency of the sanitizer. We define Ph not as the measurement of the total amount of acid or base in a pool, but as a measurement of the “activity” of the acid or alkali present. Acids are chemicals that form Hydrogen Ions( H+) when dissolved in water. Bases<Alkaline materials> are compounds which form Hydroxyl Ions (OH-) when dissolved in water. Thus, the term Ph stands for “Possible Hydrogen Ions”. When you have a high Ph it can causes cloudy water, poor or no disaffection, scale formation on the walls, clogged filters (due to scale formation), damaged heaters, mineral staining, algae growth and eye irritation. If you have a low Ph you could get corrosion and rusting, rapid loss of disinfectant, etching of plaster, damage to vinyl liners, eye irritation, etching of tile, and also tiles popping off the walls. Ph is a very important factor as you see and should always be taken serious at all times of the year.

The Ph scale runs from 0 to 14. A Ph of 7.0 is considered neutral. Values below 7.0 are acidic, Ph values above 7.0 are consider to be basic. The suggested Ph range for pool water is 7.2 to 7.6, ideally the Ph of your pool should be 7.4. MARATIC ACID can used to lower the pool’s Ph. SODA ASH has a Ph of 11.5 and is used to increase the pool’s Ph.

TOTAL ALKALINITY (TA) refers to the amount of alkaline materials in the pool water. These alkaline materials act as buffering agents and help control Ph. If the TA is too high, changing the Ph is difficult because the water resists Ph changes. High TA can also cause cloudy water, mineral stains, eye irritation, chlorine inefficiency, and calcium scaling. Water with low TA is sensitive to Ph changes, and will bounce” from high to low Ph as you try to adjust Ph. Water with low TA also tends to be corrosive, irritating to eyes, etching in concrete and plaster, corrosion of metal fittings, and can be colored (usually light green).

The suggested TA for plaster or marcite finished pools is 100-150 ppm. If you pool is fiberglass, vinyl-lined or painted, maintain TA between 125 and 175 ppm. Since TA has an effect on Ph, it is normally adjusted before any Ph adjustment is made. If the TA is below 100 ppm and Ph is above 7.2 you can raise the TA by adding “BICARB.”, If the Ph is below 7.2 add “Soda Ash” to raise Ph to proper level first. When increasing TA, the water may become temporarily cloudy for a few hours, but will clear. If the water has a TA above 175 ppm, it may be common for the area and no adjustment may be necessary. However if adjustment is needed Muratic Acid is the chemical that is used to lower TA. If the pool has a very high TA it may take many treatments to lower. When acid is added to pool water with a High TA the TA level is reduced. Also, there will be a small drop in Ph. Since a high level of TA still remains, the Ph will bounce back up its original level. Because of this treatments for TA should be spaced at least 12-24 hours apart to assure proper test results

CALCIUM HARDNESS refers to the amount of calcium and magnesium carbonate <plus other minerals> in the water. In pool water, we are mostly concerned with the calcium carbonate level or calcium hardness (CH). It should be tested for and adjusted to balance with the total alkalinity of the pool water. Although “soft” water (low CH) is considered better for regular household use, soft water is not desirable in swimming pools as it is corrosive and damaging to your pool. Low CH causes plaster etching, dingy/dull/flat looking water, and the water could be corrosive. High CH can lead to scaling, clogged filters, bleached appearance of liners, heater damage, and cloudy water.

Maintain CH at 225 to 300 ppm for plaster pools and 125 to 200 ppm for fiberglass, painted, and vinyl-lined pools. To raise CH, add “CALCIUM HARDNESS” after dissolving the required amount in 2 to 3 gallons of pool water. Lowering CH is not as easy. CH can be lowered by 11 ppm through the addition of one pound of anhydrous trisodium phosphate per 10,000 gallons of water. However, this method of treatment is not used since phosphates are nutrients for plant life and could enhance algae growth, add to alkalinity and upset the water balance. This is especially true if the source water has high CH. As pool water evaporates, the minerals stay behind and become more and more concentrated, increasing CH. Most source water has high CH, “METAL KLEAR and METAL GON” will help prevent scaling by “locking up” the calcium and keeping it in solution. If the CH is always high in your pool (above 450 ppm) consult DownTown Pools for assistance.

IRON, COPPER, and MANGANESE present in water is what generally causes the water to be colored. They can be present as metallic ions in solution which is associated with well waters, or as finely divided particles of metallic compounds in suspension which are associated with surface waters. When a pool has a high reading of metallic ions in solution make certain that the Ph of the pool is not raised above 8.2 as this will cause the metal to plate on the walls of the pool which will cause staining. Each type of metal imports its own characteristic color to the water when oxidized by chlorine or bromine. Iron produces a reddish or reddish-brown tint; copper causes the water to appear blue-green and, when manganese is present the water takes on a dark brownish-black hue. The presence of 0.3 ppm iron or 0.3 ppm manganese, or any combination thereof, WILL stain white goods or white walls of a swimming pool rapidly. 0.2 ppm,0.1 ppm will stain, but it takes just a little longer to react. Even a trace of a metallic ion will cause unsightly stains. This result is an unnecessary expenditures for draining, acid washing, and refilling. These expenses may be avoided by using a stain preventive at the time of filling or refilling by adding a sequestioning agent.


Pool water sanitation simply means killing bacteria and algae in order to disinfect and clean the water. Many sanitizing substances are available, but few are safe and effective for swimming pool use. Sanitizers used in pools must provide a residual chemical level once the algae and bacteria have been killed. It is this residual which is ready to kill any new bacteria which enters the pool, keeping the water safe for swimming.

CHLORINE in its various forms is the most commonly used pool disinfectant. In addition to killing bacteria, chlorine helps to kill algae and destroy waste material not removed by the filter system. In its natural or elemental state, chlorine is a gas. But chlorine gas is very toxic and hard to handle safely. This is why chlorine is combined with other compounds to form several liquids and solids which are effective sanitizers and safer to handle than chlorine gas. The use of chlorine in a swimming pool as a sanitizer has long been recognized. No matter what form of chlorine you use, it’s primary purpose is to combine with water to form what is called FREE CHLORINE or “Hypochlorous Acid”(HA) . It is only the chlorine in the form of HA that sanitizes and disinfects. Over 90% of the sanitizing power of any chlorine comes in form of the all important HA. HA has certain limitations. It tends to be unstable in the presence of sunlight, high temperatures and low ph levels. These conditions cause rapid chlorine loss. The amount of Hypochlorous Acid (disinfectant) your chlorine forms is dependent on the pool water Ph. As the Ph increases, the percentage of chlorine that forms into disinfectant decreases. For example, at a Ph of “8”, only 23% of the chlorine is forming disinfectant. This is one reason why Ph should be monitored. All swimming pools can develop “CHLORINE DEMAND” when insufficient chlorine is present. Dissolved iron, bacteria, perspiration, algae, pollen spores, and other organic materials create a “CHLORINE DEMAND” in pool water. If enough chlorine were added to form the suitable amount of HA to oxidize all of the pollutants present, a “CHLORINE DEMAND” would no longer exist.

BROMINE in its one form “tablet” is widely used in spas and just recently has become a choice disinfectant for a few pools. Like chlorine bromine will kill algae, disinfect and destroy waste materials in pool or spa water. In its natural state bromine is a heavy, reddish-brown liquid at room temperature. It is the only non-metal element that displays this property. Like chlorine Gas, elemental bromine is highly toxic and hard to handle safely. Bromine is combined with other compounds to form a dry organic stick approximately 3 inches long and round at a width of 1 inch. This process also removes most of the odor and potentially hazardous properties of bromine in its elemental form. Because bromines elemental state is liquid there is no need for a brominated pool to contain Stabilizer, due to the bromine not being effected by sunlight or temperature. Bromine is also very self supportive and not easily effected by outside sources or chemicals. Unlike chlorine based disinfectants bromine is not Ph dependent meaning that there will be no difference in the disinfectant strength between a Ph of 7.2 to 8.0ppm.

STABILIZER (Cyanuric Acid) As we noted, Hypochlorus Acid (usable free chlorine) is very unstable in pool water. The ultra-violet rays of the sun excite the Usable Chlorine molecules and cause a chemical reaction that gives rise to the POPULAR statement, “I can’t keep chlorine in my pool!” Science has come to the rescue with its development of Cyanuric Acid as a chlorine stabilizer. It has been found that water stabilized with sufficient levels of stabilizer retains its Usable Chlorine level longer. Stabilizer is therefore an economical factor in retaining and maintaining chlorine in your pool. Generally, it is observed that Stabilizer levels of less that 50 ppm offer little economic value in the hot Florida sun. Best results seem to be obtained by the maintenance of Stabilizer in the 80-100 ppm range. Readings as high as 110 ppm should not cause alarm if somewhat higher free active chlorine levels are maintained. To raise Stabilizer it is best to use one of two ways of adding Stabilizer to the pool water. For a marcited pool surface it is acceptable to just “broadcast” the Stabilizer granulars into the deep end of the pool, unless it is a new marcite then the following must be done. For a painted, fiberglass, vinyl-lined, or NEW marcite the customer must first dissolve the stabilizer in warm water bit by bit pouring off only the water into the pool <could take days>. To lower Stabilizer it is best accomplished by draining off a measured volume of pool water while rinsing and lightly brushing the exposed side walls and then re-filling with untreated make-up water. Remember that the only way to remove Stabilizer from the water is by diluting it.


Calcium Hypochlorite is a dry “Unstabilized” granular product with a calcium base. It is 65% available chlorine with a Ph of 12 to 13. It is slow dissolving and should be dissolved in a bucket of water prior to adding to the pool. Constant use of a calcium based chlorine will increase the calcium hardness and cause the Ph to climb upward. In the presence of heat and sunlight, it is relatively unstable and precipitates out of the water rapidly. To control this increase in calcium, Staintrine should be used on a regular maintenance program. This product is sometimes called HTH.

Sodium Hypochlorite is a “Unstabilized” liquid chlorine used in many large commercial as well as smaller private pools where handling and storage is not a problem. It has 10% to 15% available chlorine with a Ph of 13 to 14. It does not store well in heat or sunlight and should be used as soon as possible after it is manufactured. The best results are obtained when it is fed automatically through a sodium hypochlorite feeder directly into the water lines. When in the pool water, liquid chlorine is adversely affected by sunlight. For this reason it is best if you only use liquid when a well balanced Stabilizer reading is present. This product is sold fresh at 12-15% available chlorine in 2.5 gallon yellow jugs at your local pool store or in 8 to 11% version at your local hardware store in 1 gallon jugs.

Lithium Hypochlorite is an “Unstabilized” granular fast dissolving material with 35% available chlorine and a Ph of 2 to 3. It is not generally available in all parts of the country and is used primarily as a shock treatment. Most stores do not carry this type of chlorine due to its high cost.

Sodium Dichloroisocyanurate is a “Stabilized” granular chlorine with 56% to 62% available chlorine and a Ph of 7. It is highly resistant to sunlight and heat, thus remaining in water much longer that the previously mentioned chlorine. It can be hand fed or pre-dissolved and pumped through a sodium hypochlorite feeder. Although mostly used in private pools, it is becoming more popular for commercial pool applications.

Sodium Trichloroisocyanurate is a “Stabilized” tablet or stick form of chlorine with 90% available chlorine and has a Ph of 2 or 3. It is usually fed by means of a floating chlorinator or a by-pass type erosion feeder connected to the return lines of the filter system. It is a chlorine that is resistant to sunlight and has a relatively long life in the pool water. DownTown Pools carrys this product in stock under the names of KING SIZE TABS, REPLACEMENT CANISTERS and in granular form as SUPER ALGAE KILL used primarily to kill black algae.



Algae are small plants which may be found growing in swimming pools or other bodies of water whenever conditions are favorable to their growth, they may retreat into inactive particles that are carried about by the wind, which may blow them to another body of water. The atmosphere contains millions of these minute particles ready to infect a pool. Rain washes algae from the air into swimming pools. Allgae can originate, grow, and reproduce in a matter of hours, <NOT DAYS>. It is wise to start on a programmed algaecide system after the first treatment for an algae growth. There are many thousands of species of algae, each species having its own resistance to various algaecides. Algae can build up immunity to one type of algaecide and in such an instances it is necessary to change to another algaecide that is more effective.

Types Of Algae:

GREEN ALGAE is a group of algae that grows on the pool walls and in the water. They give the water a green cloudy appearance. The walls and floor will feel slippery or slimy. This creates a dangerous environment and should be treated immediately.

MUSTARD OR YELLOW ALGAE grows either on the walls or in the water. One form of mustard algae will grow on the floor of the pool. It will resemble silt and float free if you brush your hand over it. Another form will start in corners and around ladders and steps to form a yellowish slimy look. Yellow algae will most of the time seem to brush off of the walls, But that is not the case at all. Think of yellow algae as a tiny tree growing in the pool wall, when you brush the walls you are removing the leafs off the tree. But, the tree stem, trunk, and roots are still there so within a week or so the algae will return and get even harder to kill. You MUST use an algaecide to remove yellow algae, chlorine will not work alone.

BLACK ALGAE is a rooted algae Roots will penetrate into concrete or vinyl making it extremely difficult to kill. It will appear as small black spots and as the colony grows it will spread and appear to “bloom”. Unlike the other algae groups above this is one bad type and hard to kill. The basic treatment has to include a wire type brush, a 1/2 pound of Sodium Dichloroisocyanurate, and an algaecide designed for BLACK ALGAE. The brush is used to open up the protective dome the the algae builds over itself, the Sodium Dichlor is then poured on the algae so it can get into the dome, and last the algaecide is poured nearby so it can finish the job and completely kill and remove the algae from the surface.


  1. Filtration is to remove visible particles from the water as it passes through the filter media inside the filter tank or canister.
  2. Circulation is the rapid movement of the water to insure that ALL of the pool water passes through the filter frequently enough to remove visible particles.
  3. Vacuuming is the physical removing of the heavier particles that settle on the floor of your pool.
  4. Water Temperature can affect the corrosion or scaling problems that take place in the pool. Temperature does have an influence on the growth of bacteria or algae in the pool since warm water rises carrying chlorine to the surface leaving the bottom water with poor disinfectant levels.


HI-RATE SAND FILTER are easy to use and maintain. Most sand filters use a sand graded to .35 to .45 millimeters in size for best filtration. You should not backwash / backflush a sand filters until it needs to be done. You need to use the pressure gauge to determine when to backwash. The sand filter must have a pressure gauge that is working to assure good filtration. Pressure increase should be 8 to 10 pounds per square inch above the starting pressure before backwashing is needed. sunscreens, suntan oils, body oils, cosmetics, iron, calcium, copper, manganese and other organic and inorganic materials cannot be removed by backwashing. You need to use a filter cleanser at least once a year to completely remove all of the build-up of organic and inorganic wastes imbedded in the filter sand. However through studies that have been made they found that to keep a clear pool free of algae and use a sand filter it is recommended that you use a filter cleanser at least once every three months.

DIATOMACEOUS EARTH FILTERS (D.E.) Filters use a coating of D.E. over grids to trap waste and debris. For this filter to operate properly, it requires two ounces of D.E. powder per square foot of filter grid. With clean grids freshly coated with D.E., you will have there lowest pressure gauge reading. After the filter has gained ten pounds pressure, you should wash out the dirty D.E. and replace it with fresh D.E. Some D.E. filters with a “bumping” mechanism (HAYWARD PERFLEX) can be “bumped” at the ten pound pressure increase. All D.E. filters will get organic oils and inorganic mineral deposits solidified in the weave of the grid reducing even water flow and distribution of the D.E. powder. This means that at least five times a year, possibly six, you will need to use FILTER CLEAN to soak the grids in for 24 hours.

CARTRIDGE FILTERS have woven fan folded cartridges that trap waste and debris in the creases and within the weave itself. These cartridges will need to be removed from the filter tank. Large debris can be hosed off with water. Fine organic oils and inorganic mineral deposits will have to be dissolved for removal. After hosing off large debris, soak the cartridge in a solution of FILTER CLEAN, rinse well and allow to dry thoroughly prior to returning to use. It is easier for your customer to have two cartridges to rotate during cleaning.


Inadequate circulation is often ignored in pool operation. Many pool owners and operators cannot obtain clear sparkling water, even though their filters are operating properly. This may be happening because all of the pool water is not passing through the filter, but a portion of the same water is going to the filter time after time. Some pools do not have a bottom main drain and some pool owners who have main drains, cut down or shut off the water flow through the bottom main drain. This means the water is entering the skimmer and only the surface water is being filtered, leaving the bottom water in the pool not filtered and many times without sufficient chlorine. If your using a heater or solar cover, this problem is further magnified because warm water rises carrying chlorine to the surface, leaving the bottom water with poor filtration and disaffection. Main drains should be open. If your pool does not have a main drain an automatic pool cleaner of any kind would do the same purpose, and will act as your main drain. Return lines should have directional fittings (eyeballs). For maximum circulation, return “eyeballs” should be adjusted tp direct the water at a 45 degree angle towards the bottom of the pool. All return water should flow in the same counter clockwise direction. This sets up a whirlpool effect to carry the chlorine to the bottom of the pool and debris to the main drain. Often times overlooked is the weir (skimmer door) in the skimmer. All skimmers should have a properly working weir with the pool water level adjusted to allow 1/4 inch of water to flow over the weir. Without good filtration, circulation, and temperature control is will be difficult if not impossible, to achieve and maintain QUALITY POOL WATER.


Even though you may now have good filtration and circulation, which removes the majority of the debris, we still have another physical task. Some organic and inorganic particles may attach themselves to the pool walls or “fall” to the floor where they will have to be brushed or vacuumed off. This is particularly true of concrete or painted pools. Vinyl-lined pools, being of a smoother finish, probably will not need to be vacuumed as often. If there is an automatic cleaner of the type that climbs up the walls in use this problem is non-existent. The lack of such a cleaner will require you to brush the walls and vacuum the floor of the pool at least once a week to stop the growth of algae and the formation of stains over the surface.

For any questions on these topics please contact Steve, owner of Downtown Pools and the author of this text which was written for a training manual at Pool Centers U.S.A. in 1987.