Cloudy Pool Water

Cloudy Pool Water


Suspended micro-particulate matter, interfering with the passage of light is known as turbidity. It can range from an almost imperceptible haziness to a pure, milky white color. Besides being unattractive, cloudy water can prevent the rescue of swimmers in trouble and may provide no depth perception for those who would dive into the water. This particulate matter also interferes with the ability of the chemicals to properly sanitize the water.

This particulate matter can be carbonates and sulfates forced out of solution by imbalanced water, perhaps worsened by the introduction of high temperatures. The situation could also be the result of poor filtration and sanitation programs. It can indicate a problem with the effectiveness of the filter or the amount of time it’s allowed to run each day or it may point to sanitizer residuals being too low or inconsistently applied. Finally, cloudy water may result from pool water which has reached saturation. High TDS levels may not permit any more solids from being dissolved or saturated into solution.

Pool clarifiers work to coagulate smaller particles into larger, filterable clumps. Using a clarifier can be a helpful boost to your sanitation and filtration program, and may be necessary in pools with undersized or inefficient circulation and filtration systems. Adding too much clarifier can have an opposite effect however, acting not as a coagulant, but as a dispersant. Also, if you are using a metal sequestrant in the pool, be careful not to use cationic polymeric clarifiers, as it could lead to metal precipitation and staining.

Using a small amount of DE filter powder in a sand or cartridge filter can increase the efficiency of the filter. Add 1-2 cups of DE powder into the skimmer, and make note of the filter pressure. The powder will form a thin layer on top of the sand bed or cartridge, and act as a filter aid. Backwash the filter when the pressure rises 7-8 psi, or the flow rate is reduced substantially.

For extremely cloudy pools, balance the pH, calcium hardness and total alkalinity, and then shock with lithium or sodium hypochlorite, followed by constant filtration. The use of clarifiers may be helpful towards solving the problem. Otherwise, you may want to drain some of the water and dilute with less saturated fill water and / or use a flocculent to settle suspended material to the bottom for vacuuming.

Flocculants like aluminum sulfate are cationic, and attract negatively charged particles in the water. When the particle size becomes heavy enough, it sinks to the floor, forming a thick gel that is vacuumed using a vac to waste method. Used with enough shock chlorine, it can be an effective treatment for algae, or simply cloudy pool water. Vacuuming the precipitate to waste is required, which is not easily possible for cartridge filters, or filters using a push-pull backwash valve. Flocculants can also remove metal oxides, but are not especially adept at lowering metal levels in pools.

In most cases of cloudy water, there are several problems happening at the same time. Filtration may not be effective, allowing small particles to pass through or pass around the filter media. The pump may not be operating often enough, or the circulation in the pool may be poor. Water balance and sanitizer level are probably sub-optimal or neglected, and the pool may not be vacuumed and brushed regularly. Environmental conditions, such as windblown dust or pollen, heavy rains or high temperature can also contribute to a cloudy pool water problem.

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