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Thread: very fine gray sediment in pool

  1. #1
    Junior Member
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    Jun 2011
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    Pittsburgh, PA
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    very fine gray sediment in pool

    Hi everyone! I have been searching the net and this forum for the last week and half trying to determine what is going on with my pool. I have a 27' round above ground pool with a cartridge filter. There is a very fine gray sediment that settles on the bottom of the pool. It usually settles around the same area, which is the far side of the pool from the filter outlet (obviously because the water must be more still there). The sediment is very very fine. It’s not gritty. It’s not slimy. In fact you can’t really feel it at all and when you touch it or disturb the water near it, it disperses.
    I vaguely remember this same problem happening at the end of last season. I didn’t pay as much attention to it, but it was happening then also. This year when we opened the pool I started really taking notice of it, and I have declared war on it!

    My first thought to get rid of it was to vac to waste. The next day the sediment was back. I did a vac to waste again thinking this was the residual that was disturbed during vacuuming. I cleaned the filter afterwards, and it still came back. Over the next few days I did more vac to waste procedures that I can remember. I cleaned, cleaned again, and super cleaned the filter. It always comes back. I shocked the 17000 gallon pool with 5lbs of shock pool thinking that if it was organic that would certainly kill it. After the shock, I noticed more sediment, but it was white. Over the next two days, the sediment turned gray like the other stuff. After the shock, I noticed there was a fine white film on the portion of the pool ladder that was under water. I removed the ladder and ordered a new one thinking maybe after 10 years the ladder was disintegrating into the pool and causing the sediment. I also ordered a new filter cartridge. Finally I did a vac to waste again, installed the new ladder, installed the new filter cartridge and waited…. The sediment is back again.

    Wanting a closer look I was able to carefully suction up a sample of the sediment with my turkey baster (yes I know this sounds crazy…but I’m getting desperate). It looks like very very fine sand, but you can’t feel it. The pool water tests fine, except for high chlorine, which I would expect from the super shock treatment I did a week ago.
    Below are the test results from the pool store (they are as stumped as I am about what this might be)
    FC 11.16
    TC 11.16
    Alk 105
    pH 7.4
    Calc Hard 252
    Cy A 40
    Copper 0
    Iron 0
    Dissolved Solids 1000
    Saturated Index -0,2

    Here is a pic of the pool bottom...please ignore my shaddow
    [attachment=0:2dc42g25]pool bottom 2.jpg[/attachment:2dc42g25]

    I’m stumped and ready to wave the white flag….If anyone can give me any guidance I would greatly appreciate it. Thanks in advance.

    Sharon
    Attached Images Attached Images
    AG 15,500 gallons, cartridge filter, heater

  2. #2
    Senior Member
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    Aug 2010
    Location
    Dallas, TX
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    3,418

    Re: very fine gray sediment in pool

    That sediment I am almost positive is dead algae.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II T100 Sand Filter, CompuPool CPCS48 SWG, TF-100 test kit

  3. #3
    Junior Member
    Join Date
    Apr 2011
    Posts
    27

    Re: very fine gray sediment in pool

    Just a thought.. I have the same exact in my pool.. i only got it after I added solar salt to my pool for my swg.. My pool was new city water about three weeks ago.. I do not have it as bad as you but none the less have it.. but I only added 1 40 lb bag to just top off the salt level.. curious to see if you added solar salt.. hoping this is the answer.. I have gotten most of it out by using a skimmer sock.

  4. #4
    Junior Member
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    Jun 2011
    Location
    Pittsburgh, PA
    Posts
    6

    Re: very fine gray sediment in pool

    Thanks for the quick replys.

    RobbieH - If it is dead algae, then I'm guessing I would just continue my vac to waste/clean the filter routine (a couple of times I pulled the cartridge prior to vacuuming just to save the cleaning afterwards) until it is gone? Does that sound right to you?

    Ohiosteve - I haven't added any salt to the pool. I have started using a skimmer sock. Not the official ones sold at the pool store, but an old knee high over the skimmer basket. It has caught a ton of tiny stuff, but has no effect on the sediment at the bottom of the pool.

    Anyone else have any thoughts?

    Sharon
    AG 15,500 gallons, cartridge filter, heater

  5. #5
    Mod Squad Butterfly's Avatar
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    May 2007
    Location
    South Carolina
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    10,652

    Re: very fine gray sediment in pool

    You can do the Overnight Free Chlorine Loss Test (directions in Pool School) to determine if it is organics. If it is organics, shocking will solve the problem. Instructions on "How to Shock Your Pool" in Pool School.

    Welcome to the forum
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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