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Water Filtration Technical Data

Design Factors

Hourly flow rate

The normal rule of thumb is to calculate one eigth of the volume of the pool that is deeper than 1.5 m and to calculate one sixth of the volume of the pool that is shallower than 1.5 m. Add these two numbers together an increase the answer by 30% to allow for the flow back pressure / constriction provided by the filter.

For example in a 10 x 5 x 1 m deep pool with a 6 m long 1.8 metre average depth hopper the hourly flow rate should be:s

[( 6 x 5 x 1.8 )/ 8 + ( 4 x 5 x 1)/6]1.3 = 13 cubic metres per hour

Speed of Filtration

Sand Filters

In the sand filters the maximum filtration speed is normally assumed to be 50 m/h or 50 m³ per hour for every square metre of filter surface area. Sand filters are normally circular and of 0.5, 0 .6, 0 .75 or 0 .9 m in diameter

So the required filter area is = the hourly flow rate / 50

So with a flow rate of 13 cubic metres per hour the required filter area is 13 / 50 = 0.26 m2.

The sand filter area is 3.14 x dia x dia / 4 and so the filter size required is 570 mm or a 0.6 m sand filter.

Speed of Filtration in Other Filter Types

Particle Size Capability of Filtration Types

Zeolite