How do I "dial back" pump pressure?

[Silverhawk]

I got a deal on a new Hayward Perflex EC75A de filter. According to Hayward this filter should be matched to a pump with a 30-100 GPM output. However, my 2 hp pump delivers 110 GPM. What are some options to "dial back" the pump pressure to less than 100 GPM? Would installing a check valve between the pump and filter help?

Thanks in advance for any suggestions.

 

[JasonLion]

Welcome to TFP!

You really shouldn't use that filter with that pump. There are some ways to work around the flow rate issue, but they are rather more complicated than matching the pump to the filter correctly and they also waste electricity besides. Do you really need a 2 HP pump? The simplest thing might be to install a smaller impeller in the pump, which will reduce it's effective HP.

 

[Bama Rambler]

Either that filter is way too small for your pool, or that pump is way too big. Bottom line is you need to match the pump and the filter to your pool and each other.

 

[linen]

Welcome to tfp, Silverhawk

How big is your pool?

 

[Silverhawk]

I have an oddly-shaped pool with a spa. Best guess is 15-20k gallons.

Based on everyone's comments the Hayward EC75A would be too small for my set-up (Sta-Rite Dura-Glas II up-rated 2 hp pump with 2" piping throughout). Oh well, back on Craig's List it goes.

How about a 31" sand filter, such as the Hayward Pro Series with a 4.91 ft filtration area? I'm replacing a 14-year old Pac-Fab FNS-48 de filter that's given good service but is on its last legs.

 

[JasonLion]

The EC75A has a peak residential flow a rate of about 98 GPM, so it would have the same issue.

 

[linen]

The EC75A is just about right for your pool ...the real problem is your pump is too big.

 

[linen]

How about a 31" sand filter, such as the Hayward Pro Series with a 4.91 ft filtration area?

Oh I missed that you posted this. Even that filter is too small for that pump IMO, it also has a peak flow rate of 98 gpm (JL may have been referring to this filter in his last post and not the EC75A).

By the way, the EC75A has a max residential flow rate of 100 gpm (though it would be better at a max "public" design rate of 80 gpm).

Looking at the pump curves and 50 ft of head, that pump will put out about 117 gpm.

 

[scooperhsd]

Concur - you have WAY too much pump for your pool / filter - something more around 3/4 - 1 SFHP should be plenty, 1.5 at the outside.

 

[techguy]

Re: How do I "dial back" pump pressure?

I would guess that if you got the correctly sized pump, that EC75 would make your water clear as glass, very quickly and with reasonable runtimes.