These figures illustrate the maximum gallons per minute (GPM) the sized pipe will allow.

Maximum Flow Rates for PVC, Schedule 40 Pipe
Pipe Size in Inches Suction (GPM) Return (GPM)
1 22 27
1 1/4 37 47
1 1/2 51 64
2 84 105
2 1/2 119 149
3 184 230
4 318 397
5 499 624
6 720 901
8 1248 1559
10 1966 2458
12 2791 3489

Maximum Flow Rates for Copper Pipe, Type K
Pipe Size in Inches Suction (GPM) Return (GPM)
1 19 19
1 1/4 30 30
1 1/2 43 43
2 75 75
2 1/2 116 116
3 166 166
4 291 291
5 452 452
6 646 646
8 1126 1126
10 1749 1749
12 2507 2507

This chart illustrates the pump's size and their GPM ability:


Maximum Flow Rates for Copper Pipe, Type K
Pump Size (hp) GPM PVC Pipe
Minimum Pipe
Size Suction
- In Inches
PVC Pipe
Minimum Pipe
Size Return
- In Inches
Copper
Minimum Pipe Size
- In Inches
Suction / Return
1/2 70 2 1 1/2 2
3/4 80 2 1/2 2 2 1/2
1 85 2 1/2 2 2 1/2
1 1/2 100 2 1/2 2 2 1/2
2 110 2 1/2 2 1/2 2 1/2
2 1/2 120 3 2 1/2 3


If the pump is oversized for the plumbing system, you will pump less water than a smaller hp pump because the larger pump builds up too much friction and actually slows down the water flow. An example is a hp pump with 2" suction and 2" return will pump more water than a 2 hp pump with the same pluming because the plumbing is sized too small for that pump.

What we've found happens is a pool service or maintenance person will sell the owner a bigger pump, touting it as a "better deal". But it's actually a dis-service as the pump has to work harder, longer, wears out faster, uses more electricity and pumps less water. This only costs the owner more in the long run.

Does your house cleaner know how to stucco your walls? Does your house cleaner know the correct primer to use under the final coat of paint?

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