Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 3 of 3

Thread: Dark Spots on Bottom of Pool

  1. Back To Top    #1

    Dark Spots on Bottom of Pool

    I have a pebble tech pool. Was salt, but switched to chlorine. Had an algae problem 2 weeks ago, but got everything dialed in now and the water is testing well. However, I have some dark spots left at the bottom of my pool from the algae I assume? I have about 1/2 dozen that are about 1-2 feet in diameter. The pool vac won't clean it and neither will the pool brush. Is it black algae? What if I put on a glove, swam to the bottom of the pool and scrubbed the spots with a 3 inch chlorine tab? If I have to drain and fill, I'll just wait another couple years. Thanks for any advice. AZ, 15000 Gallons, Pebbletech, Chlorine, DE Filter, Hayward Floor Vac.
    IG 23K Gal, Quad DE 80, PebbleSheen, Intelliflo VS+SVRS, MT 400 NG, Stenner Pump

  2. Back To Top    #2

    Join Date
    Feb 2008
    Flower Mound, TX

    Re: Dark Spots on Bottom of Pool

    Can you please post a set of test results for us? We need to see FC, CC, CYA, pH, TA, and CH.

    In the meantime, you can check to see if it is an organic (algae) spot by scratching it with a trichlor tablet. If the stain lightens or dissapears, it is organic and you will need to shock and brush to deal with it.
    10K gallon IG gunite with waterfall; Pentair CC320P filter; WhisperFlo 2 HP pump
    TF Test Kits - Pool Math - Pool School
    "It depends."- JohnT

  3. Back To Top    #3
    frustratedpoolmom's Avatar
    Join Date
    May 2007
    SWSuburban Chicago, IL

    Re: Dark Spots on Bottom of Pool

    Black algae usually comes into play when the water balance was neglected for long periods. So when you say "2 weeks" ago...are these spots older than that? The spots are usually the size of an eraser but they can cluster together to form bigger "spots". Let us know what you find with the trichlor....
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts