2 filters or 1?

[tropic]

My pool is over 40,000 gal and I've been told that if I install 2 Filter Systems (and two pumps) that I would need to run the system half as a much. This would cut electric usage down somewhat (although I am running two pumps). Makes some sense but does anyone know if this is correct? My plumbing contractor does a lot of pools and this is his suggestion based upon my size.
Thanks for your help!
Terry

[CarlD]

It doesn't make sense to me. Sounds like the "Bigger Pump" hype to me. I run a 1 hp pump for a 20,000 gal pool, but it's two speed. Mostly I run it at low speed for about 12 hours per day. If I ran it at full speed for 6 hours a day it would cost more than twice as much at least.

What you need is to actually filter all 40,000 gallons once per day. It all comes down to gallons per minute and the max gpm the filter can take. At 27.7 gpm your filter and pump would have to run constantly. Luckily, they don't.

For example: the Hayward Super II 1.5 hp two speed can move under pretty bad conditions, 70 feet of head, enough water to filter your pool in 12 hours. Under the BEST conditions, at Low Speed, it can do the same thing, and use 1/3 the electricity.

Now I can't figure that stuff out really well, but if your pump is close to your pool and on the same level as it, you won't have high resistance.

On to the filter: A Hayward 270 filter uses 350 lbs of sand (I'll bet your pool installer wants to put in cartridge filters--they are a major PIA if you don't know how to manage them). It can filter 44,000 gallons in 10 hours and take up to 74 gpm. Usually, Hayward can tell you which pump to use with which filter.

The ONLY thing you must be aware of is the filter MUST have a higher GPM rating than the pump. Otherwise the pump will at best force too much water through to be effective and at worst ruin your filter.

I'm guessing your installer is talking about two 2.5 hp pumps as well. Total overkill. Total waste of YOUR money. The ONLY reason I know of to have two pumps is to have a second pump solely dedicated to an automatic pool cleaner--and that's a different kind of pump.

Hopefully, our actual professionals will post here and give you better guidance than I can.