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Thread: Help with low chlorine level - algae keeps coming back

  1. Back To Top    #1

    Join Date
    May 2013
    Bensalem, PA

    Help with low chlorine level - algae keeps coming back

    So I've been fighting with algae growing in my pool for a while now. Decided to buy a test kit and read some articles in the pool store as well as watching youtube videos on how to properly test my water.

    About once a week I have to vacuum the pool to get the algae off the bottom and backwash.

    I have a 24' round 4' deep above ground pool - 13,500 gallons with a DE Hayward filter. Chlorine is delivered through a floater with 3" pucks that I usually have 3 in at a time.

    I just did a test of all the levels twice to make sure I have them all correct, here are my results.

    Ph - 7.4
    FC - 0.5 to 1
    CYA - 70
    CC - 0
    TC - 2

    I've never used bleach or liquid chlorine before, and I just want to get some advice on how much I will have to add to get the FC in the 8 range target (as noted in the CYA chart).


  2. Back To Top    #2

    Join Date
    Mar 2016
    San Diego

    Re: Help with low chlorine level - algae keeps coming back

    I'm new, but I do know, first thing you'll need to do is shock your pool. Your CC is 0.0 but you deal with algae every week?

  3. Back To Top    #3
    Mod Squad pooldv's Avatar
    Join Date
    Aug 2012
    DFW, TX

    Re: Help with low chlorine level - algae keeps coming back

    Welcome to TFP!

    To kill algae we follow this process, SLAM
    TFP Moderator
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  4. Back To Top    #4
    Mod Squad YippeeSkippy's Avatar
    Join Date
    Jan 2012
    'burbs of Augusta, Georgia

    Re: Help with low chlorine level - algae keeps coming back

    I'm not sure what test kit you've used but if you do the math- TC 2 minus FC 1 = 1 to 1.5 CCs. Your pool test results are not looking like algae killing range.

    For a CYA of 70 (assuming that is correct) your FC should be 8, so with daily FC loss to the sun of aprox 2ppm, you should aim for 10ppm. Then when it drops you won't be too low which encourages algae growth.

    Just so you know, 20 ounces of 8.25% bleach will raise your FC by 1ppm.
    Maddie :) 12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
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