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Thread: Low return flow, low pressure

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    mbuice's Avatar
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    Low return flow, low pressure

    Greetings All! Please forgive this longer post.

    I know this info is in my signature, but sometimes it won't show on the phone app:

    I have a large AGP 18x33 that is buried with a 7ft deep end. I have a 250 lb sand filter with a 2-speed 1.5 hp pump. Things have been going well but yesterday I noticed a lot of debris floating. Having recently backwashed I thought that there is probably just a larger amount of leaves than normal, so I turned the pump on high and let it do it's thing. Last night, turned it back to low and things were going well. This morning, of course, floating leaves.

    Usually I can just run it on low 24 hrs/day with no problem and it gets everything. So I think to myself, probably just needs to be backwashed. I turn the valve to backwash and turned the pump on high, but I noticed that the pressure gauge is at 4.

    Normally on high the pressure is at 10, I will backwash when it hits 12-13 (Every 2 weeks or so).

    Also the water coming out of the discharge hose is not gushing out as normal either.It's still coming out at a pretty good pace, (like a garden hose?) just not as high as normal. I let it run til it's clear, rinse, and then it back to filter as usual. (I do turn the pump off any time that I'm turning the multi-port)
    So the pump is running on high and now the pressure gauge is at 0. On high it looks like it's only running on low if you look at the skimmer and return jet. Also, I'm seeing some tiny bubbles coming out of the return.

    I did a quick search and the forum posts suggest that there may be a blockage in one of my lines, so I took the garden hose and ran it through, it doesn't seem as if there's anything in the line going from the pool to the filter. Also, I would think that if there were something clogging the return line the pressure would go up, not down?

    I'm thinking I may have more than one problem, but who knows?

    Can anyone help me figure this out?

    Also, do you think it's safe to continue to run my pump on high, even with the lower flow? I just don't want to get an algae build-up on top of this.
    18 X 34 AGP 7ft deep end, 22,300 gallons. 250lb sand filter, 2 speed 1.5 hp pump. TF-100 Test Kit.

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    Pool Tool's Avatar
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    Re: Low return flow, low pressure

    Lots of things going on there, but here is a couple of guesses; check your pump impeller for debris. You can do this by shutting off pump power and placing your hand in the pump basket. With a finger or two find the impeller on the pump and clear any debris. Just make sure the pump is off and wont turn on. Air leak; i leave this one out since you are getting some flow and don't mention bubbles out of the returns.

    Zero pressure; impeller may resolve this or see if you put the mutliport back to filter and not recirculate or something else. Your gauge might also be 'pegged,' meaning that is maxed out and stuck on zero after going all the way around. See what side of the small pin the needle is on. Most gauges are cheap by design.

    Lastly, your pump should be turned off anytime you move the multiport valve handle. Leaving it on risks damage to spider gasket and the mutliport valve itself.
    16' x 32' (21100 gal), vinyl, 1.5 hp Hayward SuperPump,
    Tagelus TA60/60D Sand Filter, Raypak 399K Digital Heater, TF-100

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    mbuice's Avatar
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    Re: Low return flow, low pressure

    Hi Pool Tool, thanks for the reply. I'm going to go check the impeller now.

    I promise, I always turn the pump off before turning the multi-port valve

    18 X 34 AGP 7ft deep end, 22,300 gallons. 250lb sand filter, 2 speed 1.5 hp pump. TF-100 Test Kit.

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    mbuice's Avatar
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    Re: Low return flow, low pressure

    Okay, checked the gauge and it's not pegged, will replace tomorrow.



    I also removed the pump basket and could not feel any debris.

    My other problem is that now I want to check the filter and do a deep clean, but I have no way of removing the top of the housing because I have no way to disconnect the intake line. The installer put a union on the return line but not the intake? Is that normal?
    Guess I will be getting more than a gauge tomorrow.



    18 X 34 AGP 7ft deep end, 22,300 gallons. 250lb sand filter, 2 speed 1.5 hp pump. TF-100 Test Kit.

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    Mod Squad pooldv's Avatar
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    Re: Low return flow, low pressure

    Yep, you need a union.
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    mbuice's Avatar
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    Re: Low return flow, low pressure

    Just want to thank Pool Tool and everyone else.

    I pulled the motor away from the basket and had a much better angle to feel for debris in the impeller.

    It was completely PACKED with bristles from my pool brush.
    I replaced it a week ago, I guess I was too late on that!

    After putting everything back together, it is running swimmingly.

    Even the gauge is back at 10.

    Thanks again!

    18 X 34 AGP 7ft deep end, 22,300 gallons. 250lb sand filter, 2 speed 1.5 hp pump. TF-100 Test Kit.

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