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Thread: slight algae problem

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    Oceansol's Avatar
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    slight algae problem

    I have an 18k gallon SW in ground pool. I've had a slight algae problem for about a week now, and think I have the answer. My FC is 2, CYA 60. It's an outdoor pool, so I'm guessing I need to bring CYA up to about 70, maybe 80ppm, and FC to 4. How much CYA (dry, from Leslies) should I add, and how much dry clorine (also from Leslies) to achieve those levels, and do I also need to shock?

    Thanks in advance.

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    Texas Splash's Avatar
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    Re: slight algae problem

    Please refer to the link below in my signature for CYA/Chlorine chart. SWGs are typically between 60-80 CYA, so you don't need to go much higher. Controlling the algae will be accomplished with pure (regular) bleach (along with your SWG) - nothing else. Please refer to the SLAM link below and you'll be on your way to clearer water. Don't use or buy anything else from the pool store. Just bleach.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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    Oceansol's Avatar
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    Re: slight algae problem

    Thanks Texas Splash. So just plain old liquid bleach like qlorox?
    18,000 gallon, in-ground plaster, salt water chlorine generation, all Jandy equipment, solar water heat, paper filters, in sunny southern California

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    Texas Splash's Avatar
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    Re: slight algae problem

    Yep. That's it. Unscented/regular bleach. It can be a generic brand. Your local grocery or home improvement stores should have some decent prices for you. Just refer to the CYA chart for SWGs, find your current CYA and how much bleach you need for "SLAM", and go for it. Maintain that SLAM until you achieve the three principles stated in the SLAM instructions. At the same time, keep your pump running to circulate the water, and brush/vacuum as needed to remove any visible debris. If you have any questions, let us know.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Oceansol's Avatar
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    Re: slight algae problem

    Thanks. How do I know how much to add? Did I miss that part of the chart? In other words, how much clorine bleach per gallon of pool water? (I have 18,000 gallons )

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    Re: slight algae problem

    There is a tab that says Pool Math. Use that to calculate what you should add.
    Lisa
    Intex AG vinyl 15' x 48" 4,300 gallons due to skimmer install, Krystal Clear SF pump combo 2800 GPH, Krystal Clear SWG, Pool Blaster Max vacuum, Hayward thru the wall skimmer, TF 100 test kit with speed stir, K 1766 Taylor salt test, My SLAM Process

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    Mod Squad pooldv's Avatar
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    Re: slight algae problem

    Welcome to TFP!

    Get one of the Recommended Test Kits, I use the TF100 from tftestkits.net.

    FC of 2ppm is too low for your CYA, that is why algae is growing. It is very important to keep your chlorine level above the minimum for your CYA level at all times to prevent algae, Chlorine CYA Chart. Use the poolmath link below to calculate how much to add. I use grocery store brand plain bleach, 8.25%.

    Since algae has started growing in your water you will need to SLAM - Shock Level And Maintain your pool.

    Here are some of my fave Pool School articles.
    TFPC for Beginners
    ABC's of Pool Water Chemistry

    Here are the Recommended Levels for your pool.
    Here is the Water Balance for a saltwater pool.
    Here are the Recommended Pool Chemicals and how to add them.
    Use PoolMath to figure out how much to add.
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Oceansol's Avatar
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    Re: slight algae problem

    Thank you all. Last night I added about 4 pounds of chlorine with CYA from my remaining stock of pool chlorine from Leslies to get the SLAM started. already this morning things are looking MUCH better. I only had a slight amount of algae, so I'm hoping that it will keep going. Today I will buy regular bleach to continue the process.

    Thanks to all for helping me out here, and I wish I'd found this site several years ago!
    18,000 gallon, in-ground plaster, salt water chlorine generation, all Jandy equipment, solar water heat, paper filters, in sunny southern California

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    Oceansol's Avatar
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    Re: slight algae problem

    UPDATE.... no sign of algae, must have been a very light infection. In trying to find the cause, I discovered that my Aquapure cell sensor was reporting "NO FLOW", in which case I later discovered means that it won't generate chlorine. I called Jandy and they recommended that I check the flow sensor board in the control panel (outside). There is a tiny LED that needs to be illuminate or the sensor needs to be recalibrated. You push and hold the tiny button nearby until the light is on, and bingo, problem solved!
    18,000 gallon, in-ground plaster, salt water chlorine generation, all Jandy equipment, solar water heat, paper filters, in sunny southern California

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