Hello class ~ take your seats… today’s lecture will focus on turbidity issues in swimming pools, commonly known as cloudy pool water.
Many pool owners ask themselves “Why is my pool water cloudy”, this side of Memorial day.
The simple answer is that particulate matter, too small to be effectively filtered, has come out of solution.
I’ll ask you to remember a common 8th grade science experiment; of adding salt (or sugar) to water, until the solution reaches the point of saturation, where it can no longer absorb more salts, and the salt stops dissolving.
A cloudy pool has solids which have come out of solution, or solids that are unable to dissolve or are too small for your pool filter. But what are the causes of cloudy pool water?
Have you ever noticed that if you forget to put chlorine tabs in the pool, that it begins to turn hazy, before it goes green? Without a constant supply of sanitizer, particulate matter accumulates, and becomes visible, sometimes within hours!
One of the first ways to battle cloudy pool water is to adjust your water balance parameters, and oxidize the water with granular chlorine, or with non-chlorine shock – to kill anything organic in the water.
Especially true of smaller pools with small filter systems, one skimmer and one return, the circulation may be weak. Brushing the pool helps immensely, and for pools without a working main drain, you can set up your vacuum head/hose to draw water from the bottom.
Pool pump impellers can become clogged, as can pool pipes or valves. An obstruction like this before the pump will cause the pressure gauge to read abnormally low, and water flow rates will be noticeably diminished.
The pool filter plays a large role in restoring clarity when water conditions go south. Run your filter pump 24/7 to clear cloudy pool water. It won’t hurt the pump motor, it’s built for continuous duty.
If your pressure gauge is not rising, this indicates that the particle size is too small for your filter media, it’s passing right through! It could also mean that there are filter problems, such as being too small, or worn out, or having damaged filter media, allowing water to bypass. It could also mean a broken pressure gauge!
Using a clarifier can help to coagulate small particles, but don’t overdose, some types can act as a dispersant!
Flocculants contain particles which seek out and bond to suspended matter. In the presence of proper pH, the cluster will enlarge until the weight causes it to sink to the floor, usually overnight. To clean-up the gelatinous hydroxide that settles out, you need to be able to vacuum to waste.
If you have a friend with a DE pool filter, you can use a small amount (1-2 cups) of DE powder, added to the skimmer, to act as a temporary filter aid for sand and cartridge filters.
The Langelier Saturation Index
Developed in the 1930’s, the Saturation index is a handy way to calculate your pool water’s propensity to scale, or precipitate calcium and other mineral salts. Negative results indicate a corrosive water propensity. The formula can be used to determine if the water is dissolving, precipitating, or in equilibrium.
The formula is thus: pH + AF + CF + TF – 12.1 = ___
AF = Alkalinity Factor, CF = Calcium Factor, TF = Temperature Factor.
Refer to the chart to find the appropriate factor. A pool in perfect equilibrium has a result of 0.0 – yet anything from -0.3 to +0.3 is acceptable, and considered to be neither scaling nor corrosive.
Performing a saturation index calculation can help you see how to adjust your water balance to avoid scaling water conditions, which lead to cloudy pool water. Pentair pool products has a nice Saturation Index calculator on their website, if you’d rather not do the math!
When dealing with cloudy pool water, remember to check your filter and pump, and be spot-on with the sanitation and water balance, and water clarity should return in days, not weeks!