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Thread: Sand and dirt coming in through return, even on recirculate setting

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    Sand and dirt coming in through return, even on recirculate setting

    Hello everyone,
    I am having an issue with a lot of sand and fine dirt coming in through the return. Here's the history/background:

    • Problem was happening last year - thought it was a broken lateral and decided to change laterals and sand upon opening in spring.
    • Hired pool service to change laterals & sand. They did not buy the correct laterals, so inspected carefully and only changed sand. They said all laterals looked fine.
    • Floor still collecting a lot of stuff after opening, but spring pollen / tree debris / made it difficult to say for sure if problem persisted.
    • Purchased new Dolphin Nautilus robotic cleaner. LOVE IT!
    • After running the Dolphin 1st time, pool was immaculate. 10 minutes after filter started up, floor was a mess again.
    • Ran the Dolphin again, then ran the pool on "recirculate". Same problem, the floor was a mess after 10 minutes.
    • The residue in the Dolphin cartridges is a mix of half sand / half fine dirt and tree debris.
    • Opened the multiport, the spider gasket looks ok (I changed it last year).


    The presence of sand in the robot cartridge means that it must be coming from the filter. But the problem is happening even when on recirculate.
    The fine "dirt" that collects in areas of the floor "poufs" when brushed or touched. Could this be dead algae? Where is it coming from?

    I've been reading these forums for the past 3 years, and you have all been so very informative. Any insight you can offer on this problem is very much appreciated. Thanks in advance...

    23000 gallon 16 x 32 rectangular wood-frame pool with vinyl liner ~~ Hayward S-200 Sand Filter ~~ Hayward .75HP pump ~~ Praher top mounted multiport.

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    borjis's Avatar
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    Re: Sand and dirt coming in through return, even on recirculate setting

    Possibly the spider gasket in your multiport valve?

    check for tears or it being intact.
    16x32 IG Vinyl, 13,000 Gals. Hayward S-244T sand filter, SP2810X15 pump
    (1.5 HP motor) Raypak PR266AEN (266k btu) gas heater. TF-100 Test Kit.
    Dolphin E10 Cleaning Robot.

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    Re: Sand and dirt coming in through return, even on recirculate setting

    Quote Originally Posted by borjis View Post
    Possibly the spider gasket in your multiport valve?

    check for tears or it being intact.
    I looked at it yesterday, and it appears to be intact. The spring mechanism inside the top of the multiport valve looks a little corroded and rusty, though.
    23000 gallon 16 x 32 rectangular wood-frame pool with vinyl liner ~~ Hayward S-200 Sand Filter ~~ Hayward .75HP pump ~~ Praher top mounted multiport.

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    Re: Sand and dirt coming in through return, even on recirculate setting

    Quote Originally Posted by jmw977 View Post
    ...They said all laterals looked fine....
    ran the pool on "recirculate". Same problem, the floor was a mess after 10 minutes.....
    Opened the multiport, the spider gasket looks ok (I changed it last year)....
    This does not compute! Perhaps there is a crack in the vertical instead of the laterals, or they fibbed about the laterals, but if the spider is ok and the valve is in recirc.....???

    Is it possible the valve handle is indicating the wrong position? Recheck the spider? Check top of vertical.
    What about a broken return line and the sand is not from the filter but from fill around the pool. [wait a minute-is this AGP? if so, scratch that last idea. i'm projecting my own setup into possibilities!].
    I'll wait for confirmation that the return line is not the possible suspect....
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Re: Sand and dirt coming in through return, even on recirculate setting

    The valve handle is definitely in the correct position. Sorry, should have included "in ground" in my signature.
    There is no sand in the fill around the pool. My worst fear is that this is a cracked underground pipe, but I am definitely not losing any water.
    23000 gallon 16 x 32 rectangular wood-frame pool with vinyl liner ~~ Hayward S-200 Sand Filter ~~ Hayward .75HP pump ~~ Praher top mounted multiport.

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    Re: Sand and dirt coming in through return, even on recirculate setting

    Quote Originally Posted by jmw977 View Post
    .... The spring mechanism inside the top of the multiport valve looks a little corroded and rusty, though.
    Ah..perhaps the spring is sticking and not making a seal. or no longer strong enough to make a good seal. you wouldn't think that would result in so much sand getting by in recirc though. maybe a little, but not what i think from your description. So if it is not a cracked return line, perhaps there is residual filter sand in the lines that got there when you were in the filter position that is being cleared when you are in recirc. stretching for possibilities.
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Re: Sand and dirt coming in through return, even on recirculate setting

    Would that account for the fine dirt, too?
    23000 gallon 16 x 32 rectangular wood-frame pool with vinyl liner ~~ Hayward S-200 Sand Filter ~~ Hayward .75HP pump ~~ Praher top mounted multiport.

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    Re: Sand and dirt coming in through return, even on recirculate setting

    no, that is why my money is on a cracked return line and even though you think there isn't any fill sand, there may be some. and you probably wouldnt experience a major loss of water.
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Re: Sand and dirt coming in through return, even on recirculate setting

    Return line = underground? (My worst fear)
    23000 gallon 16 x 32 rectangular wood-frame pool with vinyl liner ~~ Hayward S-200 Sand Filter ~~ Hayward .75HP pump ~~ Praher top mounted multiport.

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    Re: Sand and dirt coming in through return, even on recirculate setting

    i forgot to ask if the sand is white like filter sand. i had sand leaking in the seam at my fiberglass steps and coping that was darker than filter sand. if you are getting white filter sand, maybe you have both problems.

    way to check leak around the spider. add dye to the water on top of sand but leave the valve in recirc. if you see the dye in the return line, there is a leak around the gasket.

    ways to check cracked return line. 1. pressure check. or 2. disconnect the valve body from top of filter and run it in recirc mode. i think you can do that. not quite sure. but if the spring isnt strong enough i know you cant. if you still get sand/dirt when the valve isnt connected to the filter, you know it isnt coming from there.
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Re: Sand and dirt coming in through return, even on recirculate setting

    It's definitely white like filter sand. Very good idea about adding dye to the top of the filter sand. I have a call out to the pool service, so I'll let them check out these possibilities. Thank you so much!

    - - - Updated - - -

    I am not sure what you mean by "pressure check" for the cracked return line. The pressure has been perfect at 12. It went up to about 15 once this season, then came right back down to 12 after backwashing.
    23000 gallon 16 x 32 rectangular wood-frame pool with vinyl liner ~~ Hayward S-200 Sand Filter ~~ Hayward .75HP pump ~~ Praher top mounted multiport.

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    Re: Sand and dirt coming in through return, even on recirculate setting

    Quote Originally Posted by jmw977 View Post
    ....

    I am not sure what you mean by "pressure check" for the cracked return line. The pressure has been perfect at 12. It went up to about 15 once this season, then came right back down to 12 after backwashing.
    i mean isolate the return line(s) and pressurize w/air to see if it will hold or if it leaks down. has nothing to do with filter pressure. easy to do but you need fittings that you probably dont have on hand. i wouldnt worry about it.
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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