Cloudy water is the most common problem faced by pool owners. Of course everyone enjoys swimming in sparkling, clean water, but proper care is required to maintain this enticing state.
So what causes cloudy water?
Pool water clarity can be affected by tiny suspended particles which cause cloudy water. These particles are so tiny they are unable to be removed by filtration, although they are still large enough to scatter light, and their size and weight prevents them from sinking to the pool floor.
Particles such as dirt, dust, and lint are generally brought into the pool by the swimmer, with leaves, bugs, and other organic material also causing problems. These particles generally repel one another so they remain the same hard-to-filter size. In cases such as this, the use of aluminium sulfate or specially-designed polymers help to solve the problem.
The alum forms a gel-like substance that bridges or sticks together. This substance then forms small bundles (called flocs) which trap suspended particles as they fall through the water. This bridging process is known as flocculation. It creates a large amount of sediment on the bottom of the pool made up of both the dirt (suspended particles) and the gel-like alum substance. The sediment is then usually vacuumed to waste rather than filtered out, because the amount of sediment is more than most filters can handle.
The polymers work in a similar way; their long molecular structure attracts smaller particles (due to the charged nature) and eventually becomes a large particle built of many tiny particles. The larger particles are therefore able to be removed from the water by filtration or by vacuuming.
To use or not to use alum
Generally, the size and weight of the larger polymer particles causes them to sink so they can be vacuumed from the pool floor. The big question is whether to use alum or not. This is not an easy question. Liquid, organic polymer water clarifiers are far better, faster and a lot less of a hassle to use than alum.
If the purpose is to clarify cloudy or hazy water, it is better to use a water clarifier than alum. If the water is really dirty - for example, if you can only see down into the water a couple of centimetres - then a one-time dose of alum may be better than multiple doses of a water clarifier. If the purpose is to make a sand filter more efficient, then alum may be the better choice.
Swimart stocks a range of Aqua-Health products which will help you to keep your pool sparkling and inviting. For more information, just ask your local Swimart expert.