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Thread: What horsepower pump to get? (Need Pump Recommendations)

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    What horsepower pump to get? (Need Pump Recommendations)

    My pump will be needing replacement soon and I have a few questions.

    I see a lot of posts telling people that their 1hp or 1.5hp pumps are too much power for their pools which are often times larger than mine.

    My pool is 11k gallons with an attached spa (presently not heated, just a jets) and my pump is a Jacuzzi Magnum Force 1.5hp pump which powers BOTH the pool and spa. I don't find the force of the water coming out of the returns to be too strong at all nor do I find the vacuum suction line to be too strong either. If anything, I kinda wish I had more powerfull force of water coming out of the return fittings as I feel it would help circulate the water a little better. I can point the eyeball almost straight up and the force of the return water wont even break the surface of the water.

    So is it that:
    a) My existing pump was an improper selection for my pool and they should have gone smaller in horsepower?
    b) The 1.5hp Magnum Force Pump of 10 years ago is equivalent to a 3/4 or 1hp pump of today?
    c) Since my existing 1.5hp pump is what has worked for 10 years without problem, I should probably replace it with another 1.5hp pump when the time comes.?
    d) There is no correlation in horsepower between different brands. One company's 3/4hp might be equivalent to another company's 1.5hp.

    ETA: And lastly, what would be a good recommendation for a pump to replace my existing pump. Please keep in mind that I would like the maximum force possible without adversely affecting my overall system's performance. And also keep in mind that I intend to add a heater at some point (possibly a heat pump). Actually, I'd like to leave enough room (power wise) in case of any other common add on (waterfall, fountain, whatever).

    Thanks.
    TFP SUPPORTER through TFTestKits.com - My Pool: South Florida, 11K gallons, In ground, concrete / Diamond Brite, Free Form with attached spa (no heater- go figure) Built around 1998, original surface, Jacuzzi Magnum Force 1.5HP pump, Jacuzzi Cartridge Filter, Rainbow 320 Tablet Feeder, Hayward Navigator Pro, Taylor K-2006 w/ TFTestKits replacemeng Reagents.

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    JasonLion's Avatar
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    Re: What horsepower pump to get? (Need Pump Recommendations)

    It is almost never worth replacing a pump that is working well. If you do need to replace the pump then you should look at two speed pumps. Running a two speed pump on low speed can save a great deal on electricity. Because of the spa, you want to stick with something that has the same SFHP or amp rating on high speed and then use low speed when the spa is off.

    a) Yes.
    b) No not really.
    c) No not really.
    d) There is some correlation, but it isn't reliable. If you know the SF rating you can compare the SFHP, which is SF times HP. Alternatively, compare the number of amps the motors are rated for.

    Waterfalls are highly variable in their pump requirements. For any significant waterfall you need a separate pump.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: What horsepower pump to get? (Need Pump Recommendations)

    From what you say in your post and if were my pool I would have two, 2 speed pumps. One for the pool and one for the spa. I read that some where on here, but how to do it with one filter? I would take it you have valves that you could use spa or pool with your exsisting pump? Do a search and type in two pumps and see what you find.
    12X18 AG, 6200 gal
    Hayward S166T sand filter, Switched back to 100 sq ft cart.
    Hayward 1hp power flo matrix two speed pump.
    Been using BBB since pool was new in 2004. Never had any problems.

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    Re: What horsepower pump to get? (Need Pump Recommendations)

    Quote Originally Posted by JasonLion
    ...
    a) Yes.
    ...
    Interesting. Can you explain to me why it is then that the force of water coming from my returns (as well as force of suction) is not very strong? I mean, it's adequate but I find it to be just barely enough at best. I certainly wouldn't want to go any weaker. Wouldn't going with a lesser HP pump result in a weaker flow of water? (assuming everything else stays the same?)
    TFP SUPPORTER through TFTestKits.com - My Pool: South Florida, 11K gallons, In ground, concrete / Diamond Brite, Free Form with attached spa (no heater- go figure) Built around 1998, original surface, Jacuzzi Magnum Force 1.5HP pump, Jacuzzi Cartridge Filter, Rainbow 320 Tablet Feeder, Hayward Navigator Pro, Taylor K-2006 w/ TFTestKits replacemeng Reagents.

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    JasonLion's Avatar
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    Re: What horsepower pump to get? (Need Pump Recommendations)

    We perhaps didn't make the distinction between spa mode and pool mode clear enough. When in spa mode, yes you do want obvious pressure from the jets, but in pool mode you don't. I don't know which of those two cases you are talking about, and should have asked you to clarify that earlier.


    In pool mode the ideal is an extremely low speed on a variable speed pump with almost no detectable pressure from the returns. The, when using the spa, turn up the speed to get the jet action you need. This is easy to do with a variable speed pump, requires some more careful selection to get right with a two speed pump, and is impossible to achieve with a single speed pump. There is also a secondary issue with skimmer effectiveness, which I won't go into here except to say that it is easily solved with a suitable control system.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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