Pump too large for my system?

[derrikm]

I have a 10,000 gal inground gunite pool, attached overflow spa, 100 st ft Hayward cartridge filter, 2” pvc throughout, 2.0 hp 2 speed pump motor. I feel that the large size of this pump is not only inefficient but also contributing to poor filtration.

Without going into a long winded story, I am unhappy with the quality of the filtration in my pool. I have spent many $$$ replacing cartridges ever 6 months, and even tried adding some synthetic DE to the filter. All with little or no effect.

Am I correct in assuming too large a pump motor in a cartridge system can cause the filter pores to widen and thus decrease the filtering efficiency? If so, I guess I’ll be looking for a new pump. If that’s the case, what size would I need, 2 speed preferred. Are there any brands or models that would be better than the rest or any I should steer clear of?

Thanks

[eljefe281]

First, your post doesn't match your signature. ;)

Does that pump also feed your spa jets?

If not, I think a two-speed 1 hp would be more than enough - possibly even a two-speed 3/4 hp.

If it does feed the spa jets, you'll have to provide some information on the number of spa jets.

[derrikm]

First, your post doesn't match your signature. ;)

Does that pump also feed your spa jets?

If not, I think a two-speed 1 hp would be more than enough - possibly even a two-speed 3/4 hp.

If it does feed the spa jets, you'll have to provide some information on the number of spa jets.

Thanks for the heads up about the signature. Yes this pump feeds the 5 jet spa as well as the pool. However we really don't use the spa at all. Plumbing is set up with a 3 way valve so I can regulate flow to my liking.

[eljefe281]

I believe the 1 hp or 3/4 hp two-speed would be plenty, but I think it would be a good idea for you to wait for some of the more experienced members on the board to chime in.

As far as brands are concerned, I guess any of the major names are good - Pentair, Hayward, Jandy.

I am getting Pentair pumps.

If you call Pentair tech support, they will help you select a pump. I imagine that's true for any of the other companies as well.

[eljefe281]

Basic steps for selecting a pool pump:

How many gallons of water do I need to turn over in one day? (Twice your pool volume)

How many hours per day will I run my pump? (Entirely up to you - 8-12 is typical)

Flow rate required = (gallons) divided by (hours) divided by (60 minutes per hour) = gallons per minute

Assume a system TDH of 45-65 feet. If your circulation system has a lot of valves in it, a lot of piping elbows, and/or a long run from the equipment to the pool, choose a number on the higher end of that range. Make your best guess. (It should be noted that this is a shortcut, but one that is fairly well accepted by the board).

Look at the pump curve for a particular pump you are considering. How much flow will it deliver at the TDH you selected? Compare that to the flow rate required you calculated above.

Note that two-speed pumps will have two pump curves, usually on the same graph. At low speed, use a TDH approximately one-fourth (25%) of the TDH you selected above. Look at the pump curve for a particular pump you are considering. How much flow will it deliver at the TDH you selected? Compare that to the flow rate required you calculated above.

[mas985]

I have a 10,000 gal inground gunite pool, attached overflow spa, 100 st ft Hayward cartridge filter, 2” pvc throughout, 2.0 hp 2 speed pump motor. I feel that the large size of this pump is not only inefficient but also contributing to poor filtration.

Without going into a long winded story, I am unhappy with the quality of the filtration in my pool. I have spent many $$$ replacing cartridges ever 6 months, and even tried adding some synthetic DE to the filter. All with little or no effect.

Am I correct in assuming too large a pump motor in a cartridge system can cause the filter pores to widen and thus decrease the filtering efficiency? If so, I guess I’ll be looking for a new pump. If that’s the case, what size would I need, 2 speed preferred. Are there any brands or models that would be better than the rest or any I should steer clear of?

Thanks

Just curious as to why you simply don't run your pump on low speed all of the time. It is oversized at 2 HP but on low speed, it should be fine.