This is a quick reference guide to solving swimming pool water problems. (Don't forget that you can find certain words on the current web page you're viewing by pressing CTRL+F. Simply type the word to look for and press ENTER.)
| Problem | Cause | Solution |
| Green/ brown cloudy water | Algae | shock treat pool , Use algaecide |
| Dust, sand, contaminants | Use a flocculent/ coagulant, increase pump cycle, check/ service filter | |
| Green/ brown clear water | Iron or copper in fill water | Use a chelating agent. |
| Black/ dark clear water | Manganese in fill water | Use a chelating agent. |
| Milky cloudy water | Conditioner level too high | Partially drain and refill pool |
| Hardness level too high Incorrect PH |
Use "hardness reducer". Correct with dry acid or Soda Ash |
|
| TDS level too high | Partially drain and refill pool. | |
| Stains on walls or floor | Manganese, copper or iron in pool water | Use a chelating agent. |
| Green hair/ nails | Too much copper | Use a chelating agent. |
| Chlorine smell | Too little free chlorine, too much combined chlorine | Chlorine (or non-chlorine) shock treatment |
| Burning eyes/ throat | Too little free chlorine, too much combined chlorine | Chlorine (or non-chlorine) shock treatment |
| Alkalinity level too low | Use sodium bicarbonate alkalinity increaser | |
| pH too high/ low | Adjust pH according to test results |
Total Alkalinity Problems
Total alkalinity is a measure of the total alkaline substances found in the pool water. For swimming pool purposes we usually determine the carbonate content of the water by measuring the level of calcium carbonate.
Total Alkalinity, or TA, should usually be kept at 80 - 120 ppm, though in high alkalinity waters this is often hard to achieve without resulting in an abnormally low pH.
Low Total Alkalinity
The results of a low TA may be one or more of the following:
- etching of the plaster, marbelite, marcite or tile grouting;
- corrosion of metal parts (pool heater, steps, scoop pole, light fittings, pole, nets...);
- staining of the pool's surfaces;
- green water;
- burning eyes and itchy skin;
- PH bounces (rapid fluctuations in pH).
Raising Low Total Alkalinity
Sodium bicarbonate (bicarb) will raise the TA without excessively raising the pH. Regular pH-up will raise the pH as well as the TA and should not be used. Care should be taken to increase the TA over a period of time, adding a maximum of 1 pound of bicarb for each 6,000 gallons of water. The bicarb can be added at this rate every 4 days, until the required level is reached.
High Total Alkalinity
The results of high TA may be one or more of the following:
- pH keeps going up despite regular addition of pH-down;
- cloudy water ;
- burning eyes and itchy skin;
- Reduced chlorine efficiency resulting in algae growth.
Lowering High Total Alkalinity
Regular small "acid shocks" with pH-down will reduce the pH while lowering the TA. This can be an extremely slow process and it may take weeks or longer to reduce high TA. One suggested method is as follows:
- turn off the pumps and allowing the water to settle;
- **slowly add the pH-reducer into one spot in the deep end of the pool; (care with liner see over)
- Allow the chemicals to "burn off" some of the alkalinity for 15 - 30 minutes (You may notice some bubbles rising to the surface. This is carbon dioxide and is indicative of the destruction of excess alkalinity.);
- Turn the pumps back on and allow the water to mix thoroughly.
The above method should be used only when the pH is high and your pool requires pH-reducer. If the pH is normal, adding a shock will reduce the pH to undesirable levels resulting in further pool problems.
**Care should be taken not to let the pH-reducer sit for too long as it will begin etching and softening the plaster, marbelite, marcite or tile grouting. It is also recommended to dilute the pH reducer in a bucket of water before adding to the pool to prevent this problem from occurring. Or add it directly to the skimmer.
Chloramines- Combines Chlorine Problems
Chloramines are the result of insufficient free chlorine and usually result in a strong chlorine odor in and around the swimming pool. Chloramines are formed as a product of nitrogen and active chlorine (hypochlorous acid - HOCl). The nitrogen is most commonly introduced into the pool water as ammonia in the form of sweat and (unfortunately) urine.
Associated Problems
Chloramines (combined chlorine) are poor sanitizers and have a gaseous tendency. The presence of chloramines (and dichloramines/ trichloramines in particular) causes the following physical symptoms:
- red, burning eyes;
- burning sensation in nose, throat and lungs;
- dry, itchy skin and dry hair;
- Breathing difficulty leading to "swimmers' asthma" particularly in young children.
In addition to these, the pool has a tendency to discolor, becoming milky or green with algae due to the low sanitizing ability of the combined chlorine.
Testing for Combined Chlorine in Pool Water
Some chlorine test kits and pool test strips allow you to determine free chlorine as well as total chlorine. Combined chlorine is calculated from these values as follows:
The combined chlorine value should never exceed 50% of the free chlorine value and should ideally be as close to zero as possible.
Destroying Combined Chlorine Compounds
A shock treatment using either chlorine or a non-chlorine sanitizer will ensure the destruction of the nitrogen compound combined with the chlorine. The pungent smell disappears and the free chlorine level goes up providing complete sanitization of the pool water.
Pool water chemistry formulae - chloramines
- HOCl + NH3 = NH2Cl + H2O hypochlorous
acid + ammonia = monochloramine + water - NH2Cl + NH3 = NHCl2 + H2O
monochloramine + ammonia = dichloramine + water - NHCl2 + NH3 = NCl3 + H2O
dichloramine + ammonia = trichloramine + water
Cloudy Pool Water
Cloudy swimming pool water is not only uninviting for swimmers, but is also indicative of problems in the pool water chemistry.
Causes of Cloudy Pool Water
Cloudy pool water is usually the result of one or more of the following:
- high calcium hardness level;
- high conditioner level;
- high pH;
- high total alkalinity;
- high level of total dissolved solids;
- low chlorine level;
- algae;
- large volume of microscopic particles in the pool water;
- filter/ filtration problems.
Clearing Cloudy Water (Depending on the Cause)
Conditioner /cyanuric acid (stabilizer): partially drain and refill the swimming pool to bring the level down to the maximum of 80ppm (or less).
pH: add pH reducer to bring the pH within the range of 7.2 - 7.6
Total alkalinity: reduce the total alkalinity according to the directions at total alkalinity problems.
TDS: reduce the Total Dissolved Solids by partially draining and refilling the swimming pool to bring the level below 1,500ppm (or less).
Microscopic particles: the pool will require the use of a flocculent or coagulant to clear the particles suspended in the pool water.
Filter/ filtration problems: backwash, wash or clean filter or filter medium. Treat or replace sand, DE or cartridge. Or call in your local “FLORIDA POOLS AND SPAS” for advice or help.
Conditioner Problems in Pool Water
Conditioner (or stabilizer) is necessary in the pool water to protect chlorine from the sun's UV rays. Its chemical name is cyanuric acid (no, it's not the same as cyanide) and forms a compound with the free chlorine giving it more durability in sunshine.
Required Conditioner Levels
The pool water should ideally have 30 - 80 ppm conditioner if you are using chlorine. Conditioner may be added separately, but is found is many ready-to-use chlorine products so in most pools this is not necessary.
Products Containing Conditioner
Many commercial chlorine products include conditioner. They are as follows:
Chlorine containing 57% conditioner by weight:
- Dichlor
- SDIC
- Sodium dichlor
- 56% chlorine granules, 60% chlorine granules
Chlorine containing 54% conditioner by weight:
- Trichlor
- 90% chlorine tablets, sticks, granules
High Conditioner Levels:
Swimming pools using dichlor or trichlor products may suffer from high conditioner levels due to the frequent addition of chlorine. Regular backwashing (once a week) helps to keep the conditioner level down, but pools requiring high doses of chlorine tend to reach the limit quite quickly.
Some states have ruled that the cyanuric acid level must never exceed 100ppm and public pools are closed down if and when this limit is exceeded.
Results of Excess Conditioner:
The following problems may result in pools with a conditioner level above 80ppm:
- cloudy, milky pool water;
- algae (despite free chlorine levels of 3.0 ppm);
- Dull, lifeless water.
Reducing Conditioner Levels
Unfortunately, the only way to reduce the concentration of conditioner is to partially drain and then refill the swimming pool to bring the level to within the recommended levels of 30-80ppm.
Preventing High Conditioner Levels
By monitoring the level of conditioner in the swimming pool, we can prevent the level exceeding the upper limit. As the level approaches 80ppm, the continued use of cyanuric acid containing products is not advisable.
In place of these products, the following sanitizers/ oxidizers can safely be used:
- liquid chlorine (sodium hypochlorite);
- Lithium hypochlorite (powder);
- Calcium hypochlorite (65% or 70% granules/ tablet chlorine);
- non-chlorine products such as persulfates.
Copper or Iron Pool Water Problems
Copper and iron may be present in sufficient concentrations in the swimming pool water that they cause problems of discoloration. They usually color the water (without making it cloudy) and can stain the swimming pool surfaces as well as the hair and nails of the swimmers.
Where is the copper or iron from?
Copper or iron can find its way into the pool from the fill water. If a well is used, the source may contain these metals in their ionic states. Mains water, while usually well purified, may pick up the metals in the pipe/ plumbing network it passes before it reaches the pool (from rusty or very old piping).
The copper or iron may be the result of corrosion of the pool's pump, heater, pipe work or other metal accessories. Nowadays pool water has very little, if any, contact with metal parts unless essential (e.g. pumps are plastic, while heat exchangers have to be metal). If the pool's pH is low or the total alkalinity is low or the calcium hardness level is low, then the water tends to be corrosive and the "rusting" of metal parts in the pool is greatly increased.
Another common source of copper is copper-based algaecides. The cheaper ones often supply copper ions rather than complexes and if too much is used, will result in lovely green pool water.
Copper or Iron - How to Tell
Testing the pool water will let you know what metal is in the water as well as how much. Copper almost always turns the water green and iron usually results in brown pool water. Iron can also be responsible for a green hue so it is not always possible to make a visual diagnosis.
Solve the Colored Water Problem
To solve the problem of colored water as a result of metals, there are two general approaches:
- Shock treat the pool to oxidize the metal, which then settles out of solution and looks like rust. The rust can easily be vacuumed out of the pool.
- Add a sequestering or chelating agent which forms complexes with the metal and prevents it from being oxidized by the chlorine.
Prevent the Problem Recurring
If the source of the copper or iron cannot be established or if it cannot be avoided, regular addition of a chelating agent or sequestering agent will ensure that any new metal arriving in the pool water will be held in an inactive complex.
Copper, Iron Manganese Pool Problems
Copper, iron or manganese in swimming pool water all cause the water to discolor without affecting the water's clarity.
If the water changes color after chlorine (or any other oxidizer) is added, the swimming pool water probably contains a metal.
Which Metal is It?
Green pool water - copper or sometimes iron
Brown pool water - iron (occasionally copper)
Purple/ black pool water – manganese
Algae Pool Problems
Algae are the most common pool water problem only because it is the most visibly obvious one. Algae in itself is not dangerous - in fact it is the main ingredient in many health supplements and tablets. Algae's danger is that it converts sunlight into food, releasing wastes that become the feeding grounds for unwanted and harmful bacteria and other micro-organisms.
There are well over 20,000 species of algae, only a few of which are encountered in swimming pool water. Algae are almost constantly entering the pool, and as soon as the sanitizer level drops too low, the algae begin to take hold and multiply. It takes as little as a few hours on a warm sunny day for your sparkling pool to develop an algae problem. The algae "spores" found in the air are from algae that has dried out (at a nearby stream, from a neighbor's pool...) and become airborne with the breeze.
Types of Algae
Algae in swimming pools are referred to by it color.
- green algae - by far the most common and relatively easy to treat;
- yellow/ mustard algae - troublesome to treat but also relatively susceptible to treatment;
- black algae - can be a nightmare to get rid of, especially in plastered pools;
- Pink algae - not algae at all, but is a fungus called Paecilomyces lilacinus that causes slimy white, pink or grey colonies.
Preventing Pool Algae
Maintaining proper water balance and minimum sanitizer levels will ensure that any algae spores entering the pool water cannot take hold. Most pools use chlorine, which should be kept at a minimum level of 1.0ppm. Using a mineral system may allow you to keep the free chlorine level at 0.5ppm without the risk of developing an algae problem.
Destroying Pool Algae
Once algae have been allowed to bloom, it is quite tiresome to destroy. The common steps to get rid of an algae problem are:
- Shock treats the pool. If you are using chlorine, aim for at least 10ppm free chlorine (10 times the recommended minimum level).
- Circulate the water round the clock if possible.
- Brush the pool and vacuum.
- Add a commercial algaecide prepared for the algae you have (green, mustard or black) according to the instructions.
- Repeat brushing and vacuuming daily if possible. Add more chlorine if the level falls below 5ppm.
- Clean or backwash your filter regularly.
pH Pool Water Problems
pH balance in swimming pools is possibly the most critical element of pool water maintenance. If you consider that chlorine's ability to do its job is directly linked to the pH, high or low levels inevitably lead to sanitization problems.
The ideal range for pH in swimming pool water is 7.0 - 7.6. The pH of our eyes is typically 7.2 - 7.4. In our experience, if the pH is kept at the same level as that in our eyes, the side-effects of burning, red eyes is kept to a minimum. The ability of chlorine to disinfect at this level is also optimum.
High pH
High pH in swimming pool water may result in one or more of the following problems:
- scaling or calcium buildup on pool surfaces, waterline and accessories;
- dull or cloudy pool water;
- clogging of filter medium or elements;
- drop in disinfection potential of chlorine resulting in algae growth;
- burning eyes and nose;
- Dry, itchy skin and scalp.
Lower High pH in Pool Water
Adding an acid to the pool water reduces the pH. The most common chemicals used to reduce high pool pH are:
- muriatic acid - typically 30% - 35% liquid hydrochloric acid;
- sodium bisulfate - granule or powder pH reducer.
Other acids that have been used in pool water are:
- sulfuric acid - raises TDS levels and adds sulfates to the pool water;
- nitric acid - highly corrosive but works well. (not to be used with liner pool)
If the total alkalinity of the pool water is within the recommended parameters of 80 - 120ppm, pH reducer should be added according to the instructions on the container. The acid should usually be added to water and mixed before dosing the pool. The pump should be running when the acid is slowly distributed around the pool.
Low pH
Low pH in swimming pool water may cause one or more of these problems:
- eroding of the pool plaster or grouting;
- corroding of the metal pool accessories (steps, heater . . .);
- staining resulting from metal corrosion;
- rapid dissipation of chlorine requiring increased dosage;
- burning eyes and nose;
- dry and itchy skin and scalp;
- Perishing of swimwear, pool toys and accessories.
Raise Low pH in Pool Water
Adding a base or alkali raises the pH of the pool water. If the total alkalinity is normal, pH increaser should be added according to the instructions on the container. The active ingredient is usually sodium carbonate.
Often low pH is a result of acid rain and occurs after periods of heavy precipitation. The normal tendency of pool water pH is to rise through exposure to wind and sunshine.
The most common cause of consistently low pH is low total alkalinity, which should always be adjusted (with sodium bicarbonate) before trying to increase the pH.
