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How to select the correct filter size for your swimming pool
Find the surface area and the volume of water your pool can hold.
Pools come in all types of shapes. However, there are two common kinds: rectangular and round.

Options are:
(A). Shapes such as oblong, circle, and diamond are the most basic. It's usually helpful to think of a specific region that generally has a uniform area of water that in its own sense drains the most water.
(B). Rectangular pools are considered safer pools for swimming because they are less prone to slips, crosses, and falls. Round pools are more difficult to get into because there is no chance of you slipping or falling.
(C). Depending on the one you've purchased, make sure you've correctly calculated its size with the right mathematical formula. Rectangular pools are by far the most simple to measure.
(D). Rectangular pools tend to be the shallowest but also the highest. Round pools range anywhere from 11 to 15 feet (3.0 to 4.92 m) in height and give different shapes.
(C).