Filtration and Water Balance

In brief, filtration removes fine to large solids from the water while pH and chlorine affect the water at the molecular level. Both affect water clarity. But it is the pH and chlorine that is critical to pool sanitization.

Filtration Methods

There are three types of pool filters: sand, cartridge, or diatomaceous earth (DE).

  1. Sand filters are perfectly adequate for the job, require little service, and are the most cost effective.

  2. Cartridges may capture finer particles but you will have to clean the cartridges and you may have to replace them.

  3. The DE filters use a powder which coats grids through which the water flows. The DE filters may capture finer particles but you will have to replace the DE powder and clean the grids. The grids may need replacing.

A clarifier product added to the water can assist filtration by combining fine particles into larger particles.

Run your filter sufficient hours to filter as well as to distribute pool chemicals.

Water Balance

  • Chlorine kills bacteria and algae. To get this sanitization chlorine is added to the water. There are other sanitizers and methods, however, chlorine is most common. The chlorine can be solid or liquid. The solid is easier to transport, has a longer shelf life, and includes a stabilizer. The liquid has an immediate impact as it does not need to dissolve. A test kit will guide you on chlorine levels.

  • After chlorine, the water's acidity needs to be adjusted. This is also called the pH level. To adjust this, typically, a liquid muriatic acid is added to the water. A test kit will guide you on pH levels. Plaster pools do well at a pH level of 7.4 to 7.6. Acid will decrease the pH, baking soda will increase the pH.

  • Other areas to be tested for may include: hardness, dissolved particles, metals, salt, available vs free chlorine, stabilizer. Focus first on the chlorine and pH levels.

  • The stabilizer is another acid type which is added to new pool water and is included in most chlorine tabs. It prevents the rapid loss of chlorine. If you backwash your pool and use liquid chlorine you will need to replenish your stabilizer.

  • Pool water needs to be replaced every few years due to local water hardness, evaporation, and other factors.

  • You can easily test for these items or you can bring us a bottle of water for testing.


We install single or variable speed motors and pumps.

  • Keep them dry.

  • Check for leaking seals. For example, not fixing an inexpensive part like the pump seal can ruin a more expensive part like the motor.

  • Turn off electrical power at main electrical panel before servicing.

More About pH

If you checked the pool water's pH then you have some idea of its acidity. Pondus Hydrogenii, potential hydrogen, is the amount and activity of Hydrogen ions in an aqueous solution. This is the "pH" in acidity tests.

Testing for pH usually involves a color scale using a phenol red indicator. Phenol red only measures levels of pH 6.8 to pH 8.4. The acidity could be way beyond pH 8.4 and you wouldn't know it. Solid metal pump impellers can dissolve to stubs in acidic water. Use acid or base demand reagents to determine how far the pH level is off from the measurable range of phenol red.

High levels of chlorine or bromine can alter your readings. At pH levels above 6.6, very high chlorine levels (10 parts per million) will react with the phenol red to create a dark purple associated with higher PH. Use sodium thiosulfate reagent to neutralize the chlorine or bromine. Then get an accurate reading. Just read the instructions on those test kits.

Backwashing a Sand Filter

Sand filters need to have the water flow reversed through the sand to remove any debri. To do this, the pump motor is turned off, a backwash valve is set to BW, and the motor is turned back on. When the outflow of dirty water clears then reverse the steps.

How often you need to BW will depend on many factors.

Building a Pool - Consider These Points

After having serviced and repaired hundreds of pools over thirty years, we'd like you to consider the following:

  • You can decline most of the bells and whistles and still have a nice pool.

  • Unless you intend to entertain the neighborhood, a ten to fifteen thousand gallon pool will suit your purposes.

  • In-floor cleaning systems have limited benefits. They blow - literally - the dirt around. Instead, choose a system that actively sweeps and vacuums debris. Consider Hayward, Polaris, Kreepy Krauly, or Baracuda products. Robotic cleaners are becoming more popular.

  • Choose a sand filter for ease of use and low cost. If you want fine filtration use a diatomaceous earth (DE) filter or a cartridge filter. DE's require more maintenance. DE powder substitutes are available. There are alternatives for better filtration in a sand filter, such as glass media, etc.

  • Plaster pool surfaces decline in a few years. Upgrade to plaster with additives or choose a pebble finish for permanency.

  • Dark pool finishes increase pool temperatures.

  • Tile your waterline to fight hard water deposits.

  • Salt systems are expensive, require more work on your part, will need replacement, have trouble keeping up in hot weather. We remove more than we install, but are great for serious pool users. Salt systems generate chlorine so the pool water is still chlorinated. Come in and talk to us, for questions, recommendations, concerns or deep thought on salt generating systems, heating, pumps, water chemistry, pool cleaners, etc.

  • Diving boards and slides come with risks.

  • Add a spa and double your costs.

  • Include deck holes for umbrellas, volleyball, basketball.

  • New pool plaster requires more brushing and filtering than the builder typically indicates. Pebble surfaces are far more durable and most likely permanent.

  • New pool water needs additional chemicals.

  • Pool surfaces continue to interact with water chemistry for years.

  • Check out your contractor thoroughly. Check licensing, insurance, previous customers.

Hot Tub Health & Safety

1. Before you enter the spa water, test the sanitation level with the provided test strips. (dip and wait nine seconds) Any FCL (free chlorine) reading above .5 ppm will indicate sanitized water. If Bromine is used the same will do. If the reading is zero ppm then add a teaspoon of spa chlorine (dichlor) and wait 45 minutes. If the reading is above 3.0 ppm, the water will be sanitized and healthy but you may sense a strong chlorine odor. This is normal for elevated chlorine readings and hot water. You will not experience the discomfort of high chlorine levels if the reading is from .5 to 1.0 ppm. (parts per million)

2. Also, note the pH reading on the test strip. This is a reading of the alkalinity or acidity of the water. You want to be sure the water is safe to enter then make sure the pH is above 7.0 (neutral). If the test reading indicates a low pH (below 7.0) then find a cup or two of baking soda and throw it in the water and wait 45 minutes. Baking soda is GOOD for water conditioning, odor removal and neutralizing acidic conditions. If the pH is too high (7.8) or higher, don't worry about it unless you have a sensitivity to the high Ph. If you do have this sensitivity then pH Down or Spa Down needs to be added until pH lowers to 7.2 or 7.4. This is a much more comfortable range.

A. Low pH (water with a pH reading below 7.0) indicates an acidic condition and may or not bother your skin (hell, which doesn't need a chemical peel) but it will dissolve the heating element because it is made of metal and acid dissolves metal.

B. The natural tendency of spa water is for the pH to lower so keep an eye on it, especially if the FCL reading (free chlorine) is elevated. High chlorine levels react with water to form hypochlorous acid.

3. Do not let the spa water foam. Bacteria and those little staph things will survive in foam. Correct the problem with a squirt of Defoamer. This puts the foam back into the water for sanitization (as long as the chlorine reading is >.5. Makes you think about those hotel spas you sat in, doesn't it. Bubbles are ok but that greasy, beige foam is the result of someone's body oils.

4. For you anal 'utes, you might want to remove the filter (under the skimmer basket, usually) and clean and rinse it thoroughly. Maybe even soak it in a little bleach. The filter is white when it is clean and brown when dirt and dead skin and body wastes are collected by it.

5. That's it for basic spa water chemistry. Most other spa additives can be used but are not necessary. There are enzymes and scents that are sold just for spas.