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Thread: Algae Problem?

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    Algae Problem?

    Greetings,

    Like many newbies to this site, I have a problem with my pool that I'm hoping to get help with. I can't get the cloudy/murkiness in our pool to clear up.
    After doing some reading here, I'm supposing that it is an algae problem. We have a 12,000 gallon, fiber glass, in ground pool with a single 75 sq ft area cartridge filter. Well water is used to fill the pool. We are running the pool 24/7, clean the filter at least 2x a day, and have tried adding clarifier, DE, and algaecide, all without any positive results. Unfortunately, we do not have a filter to waste set up and the manufacturer says that for hydrostatic reasons, we can't drain (siphon) the pool more than six inches below full. We did notice that there is now a white milky scum like substance on the filter before we clean it, but don't know if that is the result of the DE and /or if it means that we are making any progress in our attempts to clear up the water.

    Here are our stats:
    TDS: 500
    CYA: 100
    Total Chlorine: 8
    Free Chlorine: 8
    pH: 7.4
    Total Alkalinity: 142
    Adjusted Tot. Alkal.: 112
    Total Hardness: 189

    We've had the pool for four years and this is the first time we have encountered such a troublesome problem. Any suggestions to help us get the water sparkling clear again would be greatly appreciated.
    Sam
    25x25x16 L shaped concrete, 4' to 6', 21,000 gal, PLP4 - Pro Logic System Control & Aqua Logic Salt Chlorine Cell, Hayward TriStar 1 HP, 24" Sand Filter, SunHeater Solar Heating System, ColorLogic Light, Jandy deck jets.

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    Mod Squad JohnT's Avatar
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    Re: Algae Problem?

    Welcome to TFP.

    With your CYA at 100ppm, you need to keep your FC around 12ppm for best results, and it takes about 39ppm to shock the pool. See the chart in Pool School at pool-school/chlorine_cya_chart_shock I would try running at a higher chlorine level, possibly shock level to see if there is an improvement. I'd also either get your own test kit or get a second opinion as to your CYA level. CYA testing becomes difficult at high levels, and your 100ppm may be 150ppm or even more.

    Another issue can be that the dead algae just isn't getting into the filter. If you haven't been, brush the pool twice daily or if you have an auto cleaner, let it run to help stir things up so the filter can do a better job.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Butterfly's Avatar
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    Re: Algae Problem?

    Hi Sam and welcome to the forum

    What is your chlorine source?
    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.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    Re: Algae Problem?

    We've been buying stabilized shock chlorine from a pool store, never had a problem before.
    25x25x16 L shaped concrete, 4' to 6', 21,000 gal, PLP4 - Pro Logic System Control & Aqua Logic Salt Chlorine Cell, Hayward TriStar 1 HP, 24" Sand Filter, SunHeater Solar Heating System, ColorLogic Light, Jandy deck jets.

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    Re: Algae Problem?

    We've been buying stabilized shock chlorine from a pool store, never had a problem before.
    That chlorine source continues to add CYA to your pool which is why your CYA is too high, In turn, CYA that's too high now renders chlorine much less effective so what used to work for you doesn't any more.

    I would suggest you drain and refill enough of your pool to reduce your CYA to 50ppm or a little less. The chlorine will once more be effective and you should be able to manage your pool much like you did in years past.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    frustratedpoolmom's Avatar
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    Re: Algae Problem?

    Welcome!

    I did the too high CYA dance 2 summers ago. Same thing for me, everything was fine until about years 3 and 4 and then suddenly nothing but trouble...

    Since you are limited to how much you can drain at a time, you'll have to repeat the drain/refill dance several times to bring it down to range.

    I would guess DE is the filmy substance on the cart. I don't think that works very well on cartridge filters - it works better in sand filters. I'd hose the cartridge off, do you have an extra one handy so you can give this one a good cleaning - there are instructions on how to clean cartridges in Pool School.

    Your main problem is the inadequate FC - as advised, refer to the chart. Read How to shock your Pool in Pool School, but I'd begin the draining/refilling FIRST as it will be extremely difficult for you to maintain shock level with your CYA that high.
    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
    http://www.PerfectlyClearPoolService.com

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    Butterfly's Avatar
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    Re: Algae Problem?

    Hi Sam,

    The only cure for an overstabilized pool (like yours) is the drain/refill dance. As JohnT said, your CYA could actually be much higher than 100.
    It would cost lots of $$ to maintain an adequate FC level, and much more $$ to shock. Even tho it may not make you feel better, we see this situation all the time.

    Once you drain/refill to lower your CYA to about 50, you should use only liquid chlorine/bleach (or SWG) as your chlorine source.
    If you return to using the stabilized chlorine source as in the past, the CYA will climb back up and you will be in the same boat you are in now.

    I also suggest you get a good test like. The TF100 (link in my sig) is the best bang for the $$. This will put you in control of your pool. It is really very simple to maintain a BBB pool.

    It will help if you add your pool and equipment specs in your sig. You can do this thru the User Control Panel located upper left of page.
    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.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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