Swimming Pool Equipment – Factors for Choosing a Pump
Factors that help determine proper flow rates
The size of your pool filter is another factor to consider when sizing the pump. If the pool pump is too large for the filter, it can make the filter work poorly or even worse can damage the filter internals. Generally speaking, the slower the water moves through the filter the better the quality of filtration, particularly with sand or DE filters.
It is important to keep in mind that the manufacturer’s flow ratings for filters are often very optimistic. Our experience suggests that the following guidelines are much more realistic.
| Optimal Square Footage of Filter for Different Pump Sizes | ||||
| Pump Size | Flow Rate | Sand Filter | DE Filter | Cartridge Filter |
| 3/4 HP | 40 | 2.7 | 24 | 100 |
| 1.0 HP | 50 | 3.4 | 36 | 150-200 |
| 1.5 HP | 65 | 4.3 | 48 | 300 |
| 2.0 HP | 87 | 5.8 | 60 | 400 |
| 2.5 HP | 105 | 7.0 | 72 | 500 |
| 3.0 HP | 120 | 8.0 | 84 | 600 |
| Maximum Flow Rate Through Filter Media (flow per square foot of filter media) | ||||
| Filter Type | Sand Filter | DE Filter | Cartridge Filter | |
| Maximum Flow Rate | 15 GPM/sq. ft | 2.0 GPM/sq. ft | 0.25 GPM/sq. ft | |
Notes:
Sand Filters – the filter area, depth of the sand bed and the flow rate all help determine the quality of filtration.
DE Filters – the big enemy of DE filters is high pressure. We recommend under sizing the pumps wherever possible to reduce the possibility of grid damage.
Cartridge Filters – We see a lot of problems where builders install the smallest possible cartridge filters. The manufacturer’s recommendations tell what is allowable, not what is ideal. Not sure what size pump you need? Request a FREE PUMP SIZE recommendation specifically for your pool.
