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Thread: Going from single-speed to 2-speed

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    Going from single-speed to 2-speed

    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!
    30k gallon IG PebbleSheen refinished 2014
    60sqft FNS Plus DE wih Proguard Cellulose, 1.5hp 2speed WhisperFlo
    TFTestKit and Stenner fixed 10gpd on timer with bleach
    Dolphin m500

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    linen's Avatar
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    Re: Going from single-speed to 2-speed

    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.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Mod Squad Bama Rambler's Avatar
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    Re: Going from single-speed to 2-speed

    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.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Going from single-speed to 2-speed

    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).
    30k gallon IG PebbleSheen refinished 2014
    60sqft FNS Plus DE wih Proguard Cellulose, 1.5hp 2speed WhisperFlo
    TFTestKit and Stenner fixed 10gpd on timer with bleach
    Dolphin m500

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    Mod Squad Bama Rambler's Avatar
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    Re: Going from single-speed to 2-speed

    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.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    linen's Avatar
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    Re: Going from single-speed to 2-speed

    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).
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: Going from single-speed to 2-speed

    No specific reason for the oomph, I just like to have it there in case I need it. Realize that's not a rational reason.
    30k gallon IG PebbleSheen refinished 2014
    60sqft FNS Plus DE wih Proguard Cellulose, 1.5hp 2speed WhisperFlo
    TFTestKit and Stenner fixed 10gpd on timer with bleach
    Dolphin m500

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    linen's Avatar
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    Re: Going from single-speed to 2-speed

    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?
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    bobodaclown's Avatar
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    Re: Going from single-speed to 2-speed

    X2 on keeping your current or going smaller in a two speed. I have installed a two-speed 3/4 hp. Replaced a 1 hp originally. Couldn't be happier.
    17K Kidney Shaped Pool Concrete (Diamond Bright) Pool, 3/4 hp 2 speed 115V Sta-rite Duraglas PEA5D-180L/P2R5D-181L (Impeller C105-92PS Diffuser C1-216P), 1.5 piping, Pentair CC100 Filter , Heat Siphon 100K BTU Heat Pump Pool Heater, Flow meter Blue White Flowmeter Model No. F-30150P, Hayward Astrolight SP0581N, SWCG CalimarTitanium Edition TE45 , Dolphin Nautilus Plus with CleverClean, Lakeland Florida

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    Re: Going from single-speed to 2-speed

    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
    30k gallon IG PebbleSheen refinished 2014
    60sqft FNS Plus DE wih Proguard Cellulose, 1.5hp 2speed WhisperFlo
    TFTestKit and Stenner fixed 10gpd on timer with bleach
    Dolphin m500

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    bobodaclown's Avatar
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    Re: Going from single-speed to 2-speed

    Quote Originally Posted by texasmax
    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
    Check out pool school determine pump run time. It may surprise you.


    17K Kidney Shaped Pool Concrete (Diamond Bright) Pool, 3/4 hp 2 speed 115V Sta-rite Duraglas PEA5D-180L/P2R5D-181L (Impeller C105-92PS Diffuser C1-216P), 1.5 piping, Pentair CC100 Filter , Heat Siphon 100K BTU Heat Pump Pool Heater, Flow meter Blue White Flowmeter Model No. F-30150P, Hayward Astrolight SP0581N, SWCG CalimarTitanium Edition TE45 , Dolphin Nautilus Plus with CleverClean, Lakeland Florida

  12. Back To Top    #12

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    Re: Going from single-speed to 2-speed

    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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