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Thread: Pump Sizing. First time pool owner

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    Pump Sizing. First time pool owner

    G'day from the land down under everybody. First things first, thanks for providing such an excellent resource for all things pool.

    Apologies up front for the mix of metric and imperial numbers below.

    I have just moved into a new (actually about 70 years old) house that has a fairly large (approx 85,000 litre - 22,500Gal) tiled concrete pool. The equipment is very old, and pretty low-end I think, so before it goes the way of the Dodo, I thought I should research suitable new equipment.

    Thanks to TFP, I have at least got to a point now where I am balancing the water nicely - I took your recommendations and ordered the K-2006 ($100 from the U.S. but it really has been worth it). There is an old SWC installed however it does not work so I am currently daily dosing with Liquid Chlorine. The Auto Pool cleaner does not work either so I manually vacuum a couple of times a week. Bit of a digression, but just setting the scene for my lack of decent equipment...

    Anyway, my first step (I think) is to establish an appropriate sized Pump and Filter. The current pump is some Hong Tong Motor Co (yep, I have never heard of it either) 1.7HP, cheap Chinese import, capable of 500 Litres Per Minute. Last week I had to give the impeller a kick to get it going so I think it's on its last legs. The current filter is a 31inch Purex Tahitian Sand Filter that also seems very tired - the pressure gauge does not work and is a non standard size. I am getting some sand spat back into the pool so I suspect either the filter is about cactus, and/or the pump is too powerful for the filter.

    The inbound plumbing is 2inch, and, unfortunately, the return plumbing is only 1.5 inch (40mm).

    If I base my pump sizing on an 8 hour turnover of 85,000 litres, I would be looking at something in the range of 180 Litres Per Minute (LPM). A bit of digging led me to believe that the 1.5inch plumbing is going to restrict me to a max flow rate of around 170 LPM. Now for a few questions:

    1. is there any point going for a pump that can push more than the restrictions of the plumbing? (170 LPM)
    2. is an 8 hour turnover enough for a sub-tropical climate (similar to Florida I guess). I was speaking to somebody the other day and they suggested I should be aiming for a 4 hour turnover and carrying it out twice a day.

    I think once I have figured out my pump sizing, I can match to an appropriate Filter. I am leaning towards a cartridge filter as I like to keep it simple.

    In regards to pump brands, I will probably go with an Aussie made Onga pump. Actually, they were bought about by Pentair so maybe they are U.S. made now.

    Anyway, I will stop my babbling for now. Thanks again for the great site.
    Riddo
    First time pool owner, inherited some very old, cheap equipment...
    85K Litres, Tiled Concrete, 1.7 HP Hong Motor pump, 31 Inch Purex Tahitian Sand filter.

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    duraleigh's Avatar
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    Re: Pump Sizing. First time pool owner

    1. Quite the opposite. An 8 hour turnover (although we really don't emphasize turnover as we used to) is more than adequate. Any bigger pump will waste money upfront and then waste money for the life of the pump.

    2. For that size pool (without water features) a 1 HP pump will be adequate. Buying a pump too biog is a common mistake. Don't waste your money.

    PS - I know we are hopelessly backwards here in the US using our antiquated measuring units but it's what we know. It is not uncommon to skip over a question that uses metric because we have to look up the conversion. Lot of Australians this time of year but the posts that seem to get a bit better responses are the ones that convert to US first.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Mod Squad zea3's Avatar
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    Re: Pump Sizing. First time pool owner

    Hi, welcome to TFP! You want your pump to have enough power to mix and circulate the water well without overpowering the filtration system. A 1.0 hp pump should have plenty of power to circulate the water.

    As far as filtration goes, the slower the water flows the better it will filter. The larger the filter you get the longer you can go between cleanings.
    TFP Moderator
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    Vogue 21' round AG, Pentair 1 hp 2 speed pump, 36 sq ft DE filter, Hayward S180T 150# sand filter, Houston, Texas
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    Mod Squad jblizzle's Avatar
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    Re: Pump Sizing. First time pool owner

    Welcome to TFP!

    I have to agree with the rest. I was going to suggest a 1 HP as well, preferable to be a 2 speed to offer further electrical savings. Of course this assumes you have no high water flow needs for water features or a spa.

    There is an article in Pool School that discusses pump run time.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    bof's Avatar
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    Re: Pump Sizing. First time pool owner

    Hi
    Just to confuse the issue I have a 80 ton ish pool that is 19500 us gallons and use a 1 HP motor. I have been experimenting with the run times and found that as per the pool school that I could run my pump for 1 hour in the morning and 1 hour in the afternoon and my pool stayed clean. BUT the bugs and flora floated on top so I ran the pump for short periods during the pool use time just to keep it bug free.
    Living in Cyprus
    In ground overflow pool tiled 12m X 4m 19507 Us gals 16243 Imp gals
    1 Kw motor 15 cu m per min Sand filter
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    mas985's Avatar
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    Re: Pump Sizing. First time pool owner

    I am going to deviate from the group just a bit. A 1 HP pump could be the correct size or it could be much too big as well. It depends on the pump line. For example. I would not put a full rated TriStar, Super II, Whisperflo 1 HP on 1.5" plumbing. Those are powerful pumps. However, I would put a SuperFlo, SuperPump, MaxFlo 1 HP on 1.5" plumbing. I know I sound like a broken record sometimes but pumps should not really be sized by their HP labels. That can lead to an oversized pump.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Mod Squad jblizzle's Avatar
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    Re: Pump Sizing. First time pool owner

    I agree with Mark and that is actually what was in my head ... but agree we should be more specific.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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    Re: Pump Sizing. First time pool owner

    Thanks guys for the really helpful answers. I will go down the 1HP path, taking what Mark said into consideration, As we don't have any water features etc.

    The energy savings will be very welcome as we are paying around 30cents a KWH and the price increases just keep coming.

    I am also looking forward to upgrading my kit for some Trouble Free Pooling!

    Thanks again I will ensure that my future postings use imperial measurements.

    Paul
    First time pool owner, inherited some very old, cheap equipment...
    85K Litres, Tiled Concrete, 1.7 HP Hong Motor pump, 31 Inch Purex Tahitian Sand filter.

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    Mod Squad jblizzle's Avatar
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    Re: Pump Sizing. First time pool owner

    With power that high, a VS pump might save you more in the long run, but will cost about double initially.

    Another option would be one of the smaller VS pumps from Hayward. Assuming you will not have automation in the future.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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    linen's Avatar
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    Re: Pump Sizing. First time pool owner

    Welcome to tfp, riddo

    Quote Originally Posted by riddo
    Thanks again I will ensure that my future postings use imperial measurements.
    Some of us have no problem with metric...use which one you most comfortable with, but stick with either metric or imperial...mixing can cause confusion.

    I agree with jbliz, at your power costs looking at the Hayward superpump vs or maxflo vs is probably a good idea.
    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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