Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 7 of 7

Thread: New Pool Owner, First Algae Attack

  1. Back To Top    #1

    Join Date
    May 2016
    Location
    Four Oaks, NC
    Posts
    5

    New Pool Owner, First Algae Attack

    New 27' round AGP with salt generator installed in April. All of April and May the pool was crystal clear with temps in the 70s and low 80s and had to turn down my SWG to 20% because my CL levels were over 10. Family got in the pool for extended periods of time this weekend for the first time, followed by several days of mid 90s. Came home today to a green pool. My initial levels as follows:
    FC 0.5
    CC ? 0-0.5
    PH 7.5
    TA 100
    CYA 65

    Added 112oz of 10% liquid chlorine (all that I had) and vacuumed the bottom as much as I could until it got dark out. Left pump and sand filter running on high speed.

    Recheck Cl levels:
    FC 7
    CC 0-0.5

    My question is, do I need to SLAM the pool or will a sufficient chlorine level along with filtering clear it up? It is going to be close to 100 this weekend and would like to be able to safely use it. What should I do? Is it safe to get in the pool to vacuum easier? At what chlorine level should I not get in?

    Thanks a lot!
    27' Buster Crabbe Grand Sapphire AGP. 17,100 Gallons. 19" Hayward Sand Filter with 1.5 HP 2 speed Power-Flo Matrix pump. Hayward Aqua-trol SWG

  2. Back To Top    #2
    Richard320's Avatar
    Join Date
    Jan 2010
    Location
    San Dimas, CA (LA County)
    Posts
    18,768

    Re: New Pool Owner, First Algae Attack

    If it turned green, you need to SLAM. It may be a brief SLAM since you're on it, but you need to follow it through to completion or the green will be back real soon.

    You can get in the water all the way to shock level. So if you want to let FC drop a bit before people go swimming, it's your call. It will just slow things down a little. If the water is too cloudy to see the floor, it's not safe to swim in. You want to see someone on the bottom.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

  3. Back To Top    #3
    Mod Squad pooldv's Avatar
    Join Date
    Aug 2012
    Location
    DFW, TX
    Posts
    23,994

    Re: New Pool Owner, First Algae Attack

    Yes, with a green pool and almost no chlorine you need to SLAM.

    Chlorine level is set based on the CYA level and the FC/CYA Chart. FC must be maintained above minimum at all times for the pool to be sanitary and not allow algae to grow. FC must be raised to shock level to kill algae using this process, SLAM

    It is safe to swim when
    FC is above minimum and below shock level for your CYA, FC/CYA Chart
    PH is between 7.2 and 7.8
    Water is clear
    TFP Moderator
    If TFP helped you or saved you money - Become a TFP Supporter! <--Click here
    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

  4. Back To Top    #4

    Join Date
    May 2016
    Location
    Four Oaks, NC
    Posts
    5

    Re: New Pool Owner, First Algae Attack

    Thanks for the advice. I did fail to mention that the water wasn't really green, just the bottom of the pool. I did go first thing this morning and get 5 gallons of 8% bleach. The pool did not look all that bad the next morning, just cloudy and not much if any green. I put in 4 gallons and an hour later measured FC 35, it went up a bit more than I expected based on the calculator. I was shooting for 28 based on my cya of 65.

    Rechecked at 2:30 and FC was 17. I got in the pool and vacuumed while the FC was low. After finishing, I put in another gallon (all that I had left) and rechecked a few hours later, it was 21.5 . I would really like to use the pool tomorrow as it approaches 100. Do you think I'm safe to leave it fall the rest of the day and tomorrow morning then go in tomorrow afternoon? Will an OCLT still be relevant if the levels are below SLAM level tonight? There's no green and only moderately cloudy, as I can see the design on the floor form standing on the deck.
    27' Buster Crabbe Grand Sapphire AGP. 17,100 Gallons. 19" Hayward Sand Filter with 1.5 HP 2 speed Power-Flo Matrix pump. Hayward Aqua-trol SWG

  5. Back To Top    #5
    Richard320's Avatar
    Join Date
    Jan 2010
    Location
    San Dimas, CA (LA County)
    Posts
    18,768

    Re: New Pool Owner, First Algae Attack

    You can let off on the bleach to use the pool, but you should ensure it's above 10 at sundown and still run the Overnight Chlorine Loss Test. That's the only way to be sure you've killed everything. You don't want it to recover and reappear. If you don't kill it all now, the stuff that rebounds will be the hardier strains of algae.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

  6. Back To Top    #6

    Join Date
    May 2016
    Location
    Four Oaks, NC
    Posts
    5

    Re: New Pool Owner, First Algae Attack

    Thank you for everyone's help! I went from 19.5 to 19 overnight so I think I'm in the clear. pH went up slightly to 7.8 with the constant pump running so I added 16oz muriatic acid to get back to 7.5. Pool is still cloudy, but can still see the design on the bottom, so it's probably safe for the family to get in today? Considering adding some DE to the skimmer to help clear the cloudiness up quicker.
    27' Buster Crabbe Grand Sapphire AGP. 17,100 Gallons. 19" Hayward Sand Filter with 1.5 HP 2 speed Power-Flo Matrix pump. Hayward Aqua-trol SWG

  7. Back To Top    #7
    Richard320's Avatar
    Join Date
    Jan 2010
    Location
    San Dimas, CA (LA County)
    Posts
    18,768

    Re: New Pool Owner, First Algae Attack

    Quote Originally Posted by wiley975 View Post
    Thank you for everyone's help! I went from 19.5 to 19 overnight so I think I'm in the clear. pH went up slightly to 7.8 with the constant pump running so I added 16oz muriatic acid to get back to 7.5. Pool is still cloudy, but can still see the design on the bottom, so it's probably safe for the family to get in today? Considering adding some DE to the skimmer to help clear the cloudiness up quicker.
    DE sounds like a good idea. All the activity in the water will keep any fine stuff in suspension so the filter can grab it.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

Posting Permissions

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