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Thread: New construction deep sump pit question

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    New construction deep sump pit question

    Hi,

    I just 2 days ago finished construction of an 18 by 32 inground pool. It is just over 8 feet deep and under construction that put it about one foot into the water table. The ground is all very solid clay around the pool. The builder placed a deep sump pit under the deep end with a sump pump adjacent to the pool that pumps the water table out. In my uneducated opinion I think this sump pit continuously running is a waste of energy and not accomplishing much. The builder thinks I may get a floating liner if I turn it off. Maybe using it when it is very wet outside it may accomplish something, but is it really being useful?

    I am not sure about this and would appreciate some insight.

    Thanks
    Eric
    16 by 32 foot IG, 14,500 gallon, vinyl pool, cartridge filter, SWG, heat pump

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    Mod Squad jblizzle's Avatar
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    Re: New construction deep sump pit question

    It should only run when there is water. And you definitely want no water if the pool is empty.

    Can you raise the sump a bit ago it only runs when the water table is higher and more likely to cause problems?
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    Re: New construction deep sump pit question

    I guess my question should be :

    If the pool is full and the water table is not way up do I need to have this pump running every minute?

    My inground pool is built 2 feet above the original ground level with the back fill used to contour the earth away from the pool in a gentle slope, so the water table will never get close to the water level in the pool.

    I could for sure see the deep sump pit being necessary if the pool was empty.

    Thanks
    Eric
    16 by 32 foot IG, 14,500 gallon, vinyl pool, cartridge filter, SWG, heat pump

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    Swampwoman's Avatar
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    Re: New construction deep sump pit question

    In my uneducated opinion I think this sump pit continuously running is a waste of energy and not accomplishing much.
    I just spent a weekend at a friend's house who has a floating liner this year. I am pretty certain in hindsight he wishes his builder was as astute as yours

    That said, in my own deep sump, ours was built to use the existing pool pump via reversal to draw water out of the sump only during heavy rain events -- eg six inches over a few days. I open early to avoid spring flood issues, etc.

    The problem, as I understand it, with the auto pumps is that they are difficult to access when years hence they burn out. Has your builder addressed this eventuality? Do you have time yet to consider tying it into your pool pump system instead? Just a thought. Best wishes on your new pool!
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    Re: New construction deep sump pit question

    I guess I could move the pump up so it is not continuously on.

    What would an acceptable level for the water table to be at for an inground pool?

    Does a liner float when the water table is higher than the level in the pool? Or can it happen even when it is lower than the pool water?

    Thanks
    Eric
    16 by 32 foot IG, 14,500 gallon, vinyl pool, cartridge filter, SWG, heat pump

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    Swampwoman's Avatar
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    Re: New construction deep sump pit question

    Eric, I'm just guessing, but my understanding is that it is ideal to have the water table level below the bottom of the pool overall, which is not to say that the water pressure when filled will not support the walls against the counter pressure per se. I know in winter, the maintenance guys who help us close our pool (they do the equipment, I do the chemistry so that way we don't argue ) like to keep the water level as high as possible for the added weight against spring thaw, for example.

    In our case, we also have drainage around the perimeter of the pool because it was constructed at the bottom of a terrace where there used to be a cistern that handled stormwater runoff. The drainage ostensibly connects to twin french drains that run the length of the property on the north and south sides. We also have a river out front, but we're elevated part way up the hill. In my case I don't think the actual water table itself is normally near the bottom of my pool (based on how far we have to drill for the well ) but it's the ponding run-off we have to be conscious of.

    With all that said, there are folks out there who have put pools in areas where tides create a wide variance in water table height -- so this often means the water table is in fact higher than the bottom of the pool. I believe the traditional construction method to address this is the laying of drainpipe, gravel, sump pit and pump as you've described. So taking care via pump maintenance and ensuring you never empty the pool (pending water table height) seem to address the "pop up" (fiberglass) or "collapse/floating liner" (vinyl) phenom. Soil type will also have a bearing on this.
    In ground extended Grecian, 22,000 gal, Hayward 220t sand filter, vinyl liner, dolphin m4 supreme.
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    Re: New construction deep sump pit question

    I have a similar pit and I run it like a sump pump in my basement. Whenever the water level comes up, it fires up...that way I never have to stress about it. I think it also helps with keeping the water table low around my basement...so for me I vote Leave it on all the time.
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