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Thread: Pool Opened But Filter Won't Backwash

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    Pool Opened But Filter Won't Backwash

    Hello All. Wondering if anyone has some advice on a filter issue I have. I just opened my pool last weekend. Got everything fired up fine. Takes the pump a long time to prime because the equipment is about 30 ft away and 8 feet higher than pool level. It's a 2hp Pentair superflo. Normally, I very quickly go from filter, then pump off, then valve to backwash, then pump on, and I get backwash flow within seconds. However, when I went to backwash it, it took a very long time to prime to backwash (I have a Pentair Sand Dollar filter). And then after the backwash, I waited for 10 minutes to rinse but it never flowed to rinsed. The pump was running but there was nothing but churning water in the pump bowl. I got scared that I may do damage to the pump so I stopped it and went to filter, which worked fine. I vacuumed out the pool and, once again, went to backwash it. This time the pump wouldn't prime to backwash. I let it run for a long time hoping it would start, but nothing. The pump seemed to be running fine but I couldn't get any flow. So I put it back to filter and it's running fine in filter mode. Any ideas? How long can I run it in backwash waiting for flow? Thanks for any advice.

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    Mod Squad JohnT's Avatar
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    Re: Pool Opened But Filter Won't Backwash

    Do you have a check valve at your pump inlet?
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Pool Opened But Filter Won't Backwash

    Quote Originally Posted by JohnT View Post
    Do you have a check valve at your pump inlet?
    There are 3 lines that merge to one at the pump inlet; 2 skimmers lines and one bottom drain. All those valves were open.

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    Mod Squad JohnT's Avatar
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    Re: Pool Opened But Filter Won't Backwash

    Quote Originally Posted by Ltdplus9 View Post
    There are 3 lines that merge to one at the pump inlet; 2 skimmers lines and one bottom drain. All those valves were open.
    A check valve is a device that keeps the water in the line from draining back to the pool when you shut the pump off. It's pretty well required when the pump is that much higher than the water level.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Pool Opened But Filter Won't Backwash

    Hmmm. I don't think I have that. The only valves I'm aware of are the butterfly valves on the above mentioned lines. If I put a hose into the pump pot, the water will just continually drain down those lines. Those butterfly valves all need to be open when I backwash though, right? The bottom line is that I'm doing the same stuff I've always done but now I'm not getting flow. Some google research on the topic suggests it may be the multi-port valve gasket. But I would love some expert opinions.

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    Mod Squad JohnT's Avatar
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    Re: Pool Opened But Filter Won't Backwash

    The first thing I'd do is check the O-rings or gaskets on the lid and the pump basket drain. A little air leak will play havoc with priming.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Pool Opened But Filter Won't Backwash

    Yep, did that. It's good; well lubed and seated properly. How well does the basket need to be cleaned of debris? There is some debris in there, but not much. And I hate opening the lid if I don't need to. Everytime I open the lid and introduce air, I hear all the water in the line draining back to the pool and I know the pump is going to have to work overtime again to make prime.

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    Re: Pool Opened But Filter Won't Backwash

    I have a similar problem with priming my pump, except it won't do it on it's own no matter how long I let it sit.

    Here's another option - If you close all the butterfly valves except the one that leads to your skimmer, use a garden hose (on full power) stuffed into the draw line in the very bottom of the skimmer to help speed the prime - it pushes the water towards the pump quickly and once the pump primes, remove the garden hose and away you go.

    Like yourself, whenever I have to open the pump to clean the basket I completely loose prime. I've been meaning to install a checkvalve (as mentioned above) for some time, but it's one of those things that just doesn't ever seem to happen - I open the pump so seldom that the garden hose priming method works in the meantime.
    Mark
    -- Courtice, Ontario, Canada. "Cabo San Backyardo"
    12x16 3/4 inground - Hayward 3400VSP, Sand Filter, Rooftop 4x20 solar w/ Hayward GL235 automation.
    Previously installed at a neighbors, before, during & after photos HERE!

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