Water Filtration
Single-Layer Filters
Pool filters with single-layer sand have a single filtering bed with a nominal sand particle size ranging from 0.4 ÷ 0.9 mm.
The underbed, consisting of larger-sized sand particles than the filtering minerals, is often not included in Single-Layer Filters to protect diffusers or plates.
With the single-layer system, water turbidity cannot distribute evenly throughout the entire height of the filter mass but only on the first 10 – 15 cm, necessitating more frequent backwashing.
This system allows for a filtration capacity of 30 microns (particles larger than 30 thousandths of a millimeter are retained). To achieve good water quality, the use of flocculating agents is essential, and it is crucial that the filtration speed does not exceed 35 m/h.
Multilayer Sand Filters
Pool sand filters with multilayer sand, “heterogeneous filtering masses, abbreviated Filtr-Clear Culligan,” consist of three layers of overlapping filtering minerals supported by an underbed of gravel to protect the candles or plates.
The minerals with different particle sizes and specific weights are arranged in decreasing order from top to bottom, allowing the distribution of water turbidity across the entire height of the filter mass.
This technical feature allows:
Diatomaceous Earth Filters
Diatomaceous Earth filters utilize a filtration system with fossilized flour obtained from the siliceous shells of microalgae. The operation is based on the use of self-cleaning elements (Culligan patent) that support the diatomaceous earth layer.
The diatoms, evenly distributed on the surface of the filtering elements, trap water turbidity from the pool, making it crystal clear. The low filtration speed, 5 ÷ 6 m/h, allows achieving a filtration capacity of 0.5 – 1 micron (particles larger than 0.5 thousandths of a millimeter are retained), without the use of flocculating agents.
The water consumption for diatomaceous earth filter backwashing is reduced, significantly lower than that of a sand filter.
