Does my pool need larger pipe?


Active member
Apr 6, 2019
It's a kidney shaped pool, and I calculated it's about 17,500 gallons. Right now it has 1.5" pipe throughout, all the way until it gets to the 2HP pump and DE4800 filter, both which are made for 2" pipe.

There is one main return and that is 25' from the pump. The skimmer is about 75' from the pump. I can't say for sure, because I inherited this pool, but I would guess there are 5 90 degree elbows from the skimmer to the pump, or 4 90 degree elbows and 2 45 degree elbows.

I don't know if the previous owner installed a larger pump because he needed it or perhaps he just didn't know what he was doing. If I was worried about wasted energy costs, would replacing the pipe with 2" allow me to move to a smaller HP pump? I am thinking it might now because the skimmer and returns are all sized to 1.5" creating a bottleneck.


TFP Expert
Mar 2, 2011
As long as you keep the water velocity below 6 ft/sec on the suction and below 8 ft/sec on the pressure side of the pump, you should be fine.

  • Size.......6 ft/sec......8 ft/sec.
  • 1.5"...........38...............51 gpm
  • 2"..............63...............84 gpm
  • 2.5............90.............119 gpm
  • 3.0".........138.............184 gpm
If you don't need the flow, just keep the flow below 38 gpm.

You should switch to a variable speed pump and run as slowly as possible.


Gold Supporter
Mar 21, 2016
Atlanta Ga
2hp seems like a lot, like James said switch to a VS pump. I replaced a 1.5HP super pump with a 1.65VS and now my filter pressure is 4 compared to 16 with the old pump. I did before and after electric bill comparison the best I can and it dropped a lot


Active member
Apr 6, 2019
Right now the pressure on my DE filter, relatively newly replenished is about 23 PSI. Does this change anything?

what size pump would i need at a minimum? 1 hp? 1.5 hp?


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
a 1 hp single speed is enough. a 1.5 hp 2-speed may be your best bet in terms of saving energy and still having a very strong pump. That would be my choice.

A 1.5 hp vs would also be a good choice if you don't mind the up-front cost.
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