1/2 HP Pump will work well for almost any pool... LONG POST

New guy here, and have been reading, and reading and reading all the GREAT info here. Looking at getting a AG pool for the first time, so I have been doing my homework.

I have decided upon an 18'x33' AG, resin pool. From what I could figure out with a 52" height it would contain about 18,000 gallons of H20. I read the, "What About Above Ground Pools?" intro and the concerns about mismatching the wrong pump HP with the wrong diameter filter which causes excessive use of electricity and improper filtration, as noted below:

"A combination that will work fairly well for almost ALL above ground pools -- regardless of pool size -- is a 1/2 HP Hayward "Super" pump (mfg. model #SP2600X5), a 22" Hayward "PRO" sand filter (mfg. model #SP220T), a Hayward 1.5" "Vari-Flo" multiport valve (mfg. model #SP071113), and a cord set (#SPX1550WA [25 ft long] or #SPX1250 [6 ft long]). 1999 list price on this combo is $764.00. Any pool dealer in the US or Canada can sell this combination to you. You'll also need hoses, connectors and . . . 250 pounds of filter sand. Make absolutely certain that the sand comes in bags that are factory labeled as filter sand, and make sure that the pump and filter have exactly the model numbers shown above. This combination can be used either as original equipment, or to replace what you've got now.

Some of you may think, that since you have a larger aboveground pool, you need a larger pump and filter. This might be true, but unless you have a maindrain or two skimmers AND have two return inlets, there is little point. Most above ground components, particularly skimmers, aren't designed to handle more than about 40 GPM. Putting a larger pump and filter on will simply waste more electricity: there's no where for the extra flow to go".


If a 1/2 HP pump with a 22" sand filter would be matched with the 18,000 gallon pool that I am interested in would it be adaquate? I think I understand the principal behind the 1/2 HP pumps output would be most efficient to the 22" sand filters capabilities. However, is it not correct that the turnover of the water in the pool (18,000 gallons for the pool I'm interested in) would need to be once in 24 hours? I think I have even read on this forum that some people recommend two turnovers in a 24 hour period.

I found a cool link to a pool pump cost calculator here: http://www.pentairpool.com/pool_pump_calc/index.htm So, using the 1/2HP principal the 1/2HP pump, to turn over 18,000 gallons of H20, one time, would have to run for 13.8 hours. WOW Seems like a lot of run time! THIS IS WHERE MY QUESTION ARISES... However, since the 1/2 HP pump is correctly matched to the 22" sand filter then you would be getting +or- 100%filteration? So, does that mean that you would be able to run your pump less than 13.8 hours, maybe 6 hours, and only have half of a turnover of the 18,000 gallons of H2O?

I checked the rate from my Electrical co-op and am charged .10 a kilowatt a hour. Using the pump cost calculator at http://www.pentairpool.com/pool_pump_calc/index.htm The cost for a 1/2HP pump for 13.8 hours a day is $1.38 or $503.74 a year. However, the cost for a 1/2 HP pump for 6.9 hours a day is $.69 or $251.86 a year.

I understand that there are many variables such as use of pool, geographic location, chlorine maintenance, etc... Playing with the pool pump calculator and increasing HP from 1/2HP to 2HP for a 18,000 gallon pool, with one turnover would take 4.6 hours at $.92 cents a day or $337.61 a year. Using the same theory above, IF YOU HAVE THE CORRECT HP PUMP WITH THE CORRECT DIAMETER SAND FILTER FOR THE 2HP PUMP, could you not reduce the turnover to half the amount of time say 2.3 hours, which would be $.46 a day or $167.92 a year?

I also read this in the intro:

"Some of you may think, that since you have a larger aboveground pool, you need a larger pump and filter. This might be true, but unless you have a maindrain or two skimmers AND have two return inlets, there is little point. Most above ground components, particularly skimmers, aren't designed to handle more than about 40 GPM. Putting a larger pump and filter on will simply waste more electricity: there's no where for the extra flow to go."

Furthermore, to accomodate (the increased 2HP PUMP) flow how hard would it be to just add another skimmer and another return inlet as suggested above? I am just trying to understand the logic for pool pump size and filter optimization. By no means am I trying to discredit anybody or any information posted here. I know nothing about pools, pumps, filters, or matching them. I'm just looking for advice... Please educate me...

I think what you're missing is that you have to consider the amp draw on the pump. A higher horsepower pump means larger diameter plumbing and more amperage draw.
Most residential pools circulate water once every 8 hrs. But everyone has their own methods. There are some that will run a small horsepower pump 24/7 because it is very efficient and provides the best filtration and chemical dispersion. Then there are some that run the minimal run time necessary to turn the volume over once a day, depending in the flow rate of the pump.
Some will run their system on multiple times throughout the day, depending on their pool use. For instance, if you have a waterfall, you may want this running first thing in the morning for your early morning enjoyment. Then have the pump turn off, then back on before you get home for you to use. This is usually a 4 hr in the morning and 4 hr in the evening.
Finally, there is a two speed pump that can be used to run at low speed for the most economical circulation, then on high speed for a suction side cleaner or water features, and back to low speed.
There's no particular way to do this, other than what is correct for your pool use.
My recommendation is that whatever size pump/filter combo you select,make sure you have your pipe sized properly too.