waterman2000

There are many incorrect assumptions about swimming pools & the filtration thereof. I will try to shed some light on the subject.

Filters.

The purpose of a pool filter is to PRIMARILY prevent the dead bodies of bacteria from re-entering the pool. These dead bodies act as food for other living bacteria.

The SECONDARY purpose is to remove other solids from the pool.

Many people opt for the common 'spherical' shaped sand filters as they are cheap & readily available. They have 2 inherent problems;

1. Because of their shape, 'bio scum' builds up at the 'equator' of the filter. This scum can help to cause bacteria to flourish if the pool is not disinfected correctly. As a result, ear, eye & mouth infections can become prevalent. The 'bio scum' can only be removed by stripping the filter, cleaning out the scum & replacing the old sand with new sand. With this type of filter, this procedure is recommended annually.

2. Again because of their shape, the full volume of sand is not used for filtration. They are inefficient.

Don't forget to 'backwash' your filter for at least 5 minutes EVERY DAY.

The better style of filter is one of a cylindrical shape. It is long & thin so the water has to pass through a longer distance of sand, thus better filtering. Bio scum will not easily form in these filters due to the filter shape. These filters are very efficient but more expensive.

Filter Media.

Cartridge filter media is good but restricts the water flow as the filter becomes more clogged. This restricted water flow will have a detrimental affect on the rate of pool disinfection. So, cartridge filters need to be constantly cleaned, at least every 72 hours of operation.

Sand is also a good filter medium as it has a two-fold action...as well as restricting solids etc, the sharp edges on the sand help to kill certain bacteria that chemical disinfectants have no affect upon.

But be careful...normal silica sand is not very good at doing this. The only sand that has a proven 'kill' factor is Quartz sand...very long & very sharp edges.

Disinfection.

Chlorine is widely used but least understood. Whether you add the chlorine to your pool by hand or whether it is ionised into solution by electrolysis & Salt, makes no difference.

What must be understood is this;

1. The ability for chlorine to disinfect (kill) in water, drastically decreases when the water temperature approaches & exceeds 28 degrees Celsius. Therefore, monitor your pool water temperature...especially if you live in Thailand.

2. Chlorine is an ineffective disinfectant in solutions that have a pH of greater than 8.0.

3. 'Free chlorine' is the measure of the available chlorine that can actively disinfect. The minimum level for a domestic pool should be about 2.0 ppm (parts per million) & the maximum should not exceed 5.0 ppm. Skin, eye & mucous membrane irritations can ocur at levels as low as 3.0 ppm.

4. If your pool has the correct pH, water temperature & free chlorine levels, you SHOULD NOT be able to smell any chlorine. If you can smell chlorine, in actual fact, you are not smelling chlorine. What you are smelling is Chloramines, which is the result of Free chlorine reacting with ammonia that is excuded by humans. Chloramines have absolutely no disinfection power whatsoever. If you smell chlorine, it's time to get out of your pool & test the water again.

Pumps

As an absolute minimum requirement, your pump should be sized so that it is capable of pumping the complete volume of pool water in no more than 2 hours. The bigger pump, the better. The less the 'turn around' time, the better the disinfection rate will be. The pump should be running at least 12 out of every every 24 hours.

Testing.

Test the pool water after;

1. There have been strong winds.

2. There has been rain.

3. There have been a large number of people in the pool. Generally, a pool needs at least 8 hours to recover from any of these things.

In addition, a 'Bromine Bank' is advised if using a chlorinated pool. Bromine has good 'kill' power & lasts longer than chlorine. Basically, it picks up where chlorine leaves off. Further, a Carbon Dioxide injection system will easily & automatically control the pH so that the Chlorine/Bromine disinfection can work to the highest efficiency. An expensive system to initially install but does save on elbow grease.

The use of Ozone is not desirable due to the corrosiveness of such a system.

UV filtering needs to be VERY carefully designed for the individual installation as the type of UV globes used are very important. Also, filtration is VERY important with a UV disinfection process. In any case, a Bromine Bank is always prescribed with the use of a UV disinfection system.

If you are concerned with the health of your pool users, these guidelines are helpful.

This is some of the worst, so far off the mark it's not funny advice I've ever heard.