what size pump


New member
Jun 18, 2009
i debated for a year if i was gonna keep this pool or not..come to find the pump i had is shot and will be buying a new one this week so i can get her up and running again..the pool is ag 18x33 with a 200lb sand filter skimmer and drain in the far end and is around 18k gal. of water..the filter is a aquatools...i found a good price on a 1.5 hp is this too big..its hotter then heck in michigan i cant wait to get her up and running again


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
I imagine a 1.5HP pump is way too big for your 200lb filter. Typically a 300lb sand filter is about right for a 1HP pump. You can probably get by with a 3/4HP pump unless you need extra flow for an automatic cleaner.

Jersey Devil

Platinum Supporter
Aug 4, 2007
Jackson, NJ
If your signature specs are accurate, your old pump moved 44 gpm. I assume this was at a nominal "clean" filter operating pressure of somewhere between 10-15 psi gauge reading (note: 1 psi = .43 feet of head). This means that you would pump about 2640 gph, turning your pool over once in about 7 hours. My advice is to buy a new pump to match that performance and run it about 10 hours per day, turning your pool over 1.5 times (which is more than the minimum recommended in Pool School, but I like the results I get by filtering more than the minimum.)

It is not only horsepower that dictates flow, but pump design. Some pumps are more efficient than others, so check the flow characteristics, not just the hp before you buy. I would go to http://www.haywardnet.com/aboveground/products/pumps/ as a reference. I think you can probably get away with 3/4 hp, but if in doubt I would go to the next size upwards (1hp).