Going from single-speed to 2-speed

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texasmax

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May 24, 2010
200
Dallas, TX
Will probably swap out my 1.65bhp single-speed for a ~2.2bhp 2-speed (for the sake of saving some electricity by running primarily at low-speed) . A few questions-

I've currently got a 60sqft DE filter. On the current pump, I'm measuring in the ~70gpm neighborhood. I need to look it up but I imagine the filter has a minimum flow requirement, and at low speed (if I go low speed for an extended amount of time for daily circulation and filtration) I'll be well under that. Does this present any problems? Or will I just be less efficient with my filtration? I'm guessing the issue is the water will be concetrated in the lower half of the filter and I'll be operating effectively with a lower sqft.

I've also got a booster-driven Polaris cleaner, the standard 3/4hp pump. Any reason this can't be running at the same time? Will the Polaris be consuming most of the flow (which is fine as it's all going the same place anyway).

Is backwashing (when I don't do a full breakdown and clean) the only reason I'd need high-speed anymore?

Thanks all!
 
Post a your current pump make/model.

Generally you want to select the same hp (or more accurately the s.f. X hp = sfhp) when replacing a motor.

Unless you are backwashing, there is no minimum flow requirement, in fact generally the lower flow the better. What model DE filter do you have?

If you do not have any high volume water features, you may even want to consider going with a smaller motor and smaller impeller for your current pump to save electricity.
 
First, why are you going to a larger pump? If anything you should stay the same.

There practically is no minimum flow rate for filtering through a DE filter. The only minimum flow requirement is enough to precoat the grids and that's extremely low. Low speed on a small pump would be more than enough.

As for the booster, You'll just have to try it. I suspect it'll be fine because those are low flow high pressure pumps.

backwashing is about the only thing you'll need high speed for. You may want to run it a short time to improve skimmer action.
 
Pentair FNS Plus 60sqft and a WhisperFlo WF-26. Meant to say sfhp when I said bhp :). I've got no water features; there's a spa that's the same height as the pool but that's getting filled in in a few months. If I'm going to downsize (to 1sfhp?), I'd rather just get the 2-speed, possibly larger than what I've got currently, so low speed is 3/4 sfhp, and with high speed I've got a little more oomph than I've got today (and trying to figure out if I'd need a bigger high speed to make low speed 3/4sfhp and not 1/2sfhp. And would I need a 2hp to get that 3/4 and not 1/2 low speed (trying to look now).
 
Stay with the size you have but in 2-speed or even go to a 1sfhp in a 2-speed model. You don't need to oversize the pump to try and raise the low speed hp. Low speed is approx 1/6th the hp of the high speed side.
 
Why do you want/need the "oomph"? Without having any high volume water features, you should generally run as low a speed as possible and maybe run just a little longer then you do now (may not be needed).
 
I was just curious, since it is not uncommon in the industry to needlessly oversize pumps. The easiest route is probably to just replace your existing motor with a 2-speed version. Is yours supplied with 115 or 230 volts?
 

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texasmax said:
Yup, I'm not under suggestions from a PB or anyone else; I just feel like I "need it". I probably just need to get over the hump over running low speed fr longer hours and then I think I'll be fine :)
Click to expand...
Check out pool school determine pump run time. It may surprise you.


Sent from my AT100 using Tapatalk HD
 
Thanks all for the replies and advice. I've got a 32k gallon pool, with 4 eyeballs, and my mortal fear is that I'll have dead spots where the water just isn't moving through (though running the Polaris a reasonable amount of time should resolve that, if it even needs resolving).
 
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