The diatom filter
The diatom filter is the most advanced filter on the market today. It works by organic chemistry, due to the presence of diatoms, which are microscopic, unicellular algae.
This is a state-of-the-art filter, giving your pool the most efficient filtration available. It uses the system of diatoms, or fossilized microscopic algae powder. These algae are naturally present in all humid areas. When they are fossilized (called 'diatom earth') they are used in a wide range of cleaning products.
This filter consists of a small tank where water enters from the outlet of a pump. The algae are positioned in the body of the filter between two skins made of nylon, polyester, or more recently, synthetic resin. These filtering units, filled with diatoms, are layed on top of one another. When the water from the pool passes through the skins, the floating diatom particles capture the dirt.
An excellent filtration is obtained (2 to 5 microns), but this type of high-performance filter is very exigent. When the water has a high lime content, the diatoms are quickly saturated and therfore the filtration is blocked. Another inconvenience is that they need time to purify the water. When the flow of water exceeds 5 cubic metres per hour, the filter gets dirty too quickly and clogs up. Big pools with powerful pumps should therfore be fitted with a less fine filtering system, otherwise they cannot pump to their maximum capacity.
Another big disadvantage is that, unlike the sand filter which regains its original efficiency simply by cleaning, the filtering elements of the diatom filter need to be replaced regularly. On average, when the gauge increases by 0.5 bar, the diatoms require changing. Professionals recommend around 3 litres of diatoms per square metre of filtering surface. Every time the diatoms are replaced, the filtering skins should also be replaced. If the pool is used often, the cost of maintenance may therefore be quite expensive. To change the filtering elements, you need to dismantle and clean the filter, which can be a long and tedious process.
On the positive side, the quality of filtration by diatoms is excellent and the process is natural. You can therefore save on the expense of buying treating products. Furthermore, the diatom filtering system doesn't consume much water, unlike the sand filtering system.