Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 14 of 14

Thread: Algae is back

  1. Back To Top    #1

    Join Date
    Oct 2007
    Location
    Parkland, FL
    Posts
    727

    Algae is back

    some of you may remember me battling algae for quite a bit and finally buying the TF Test kit. Well my pool was good for about 2 months and now I have algae starting to grow again. SWG has been going the whole time so not sure why it started to grow again. I did get lax on the PH and it did creep up to like 8.5 or so.

    So latest tests.

    FC 5.0
    CC 0
    PH 8.5
    CYA 40
    CH 470
    TA 120
    8000 gal diamond brite pool with 650 gal spillover spa, Pentair 3hp VS pump. Jandy Cartridge filter and Jandy Heat Pump. Jandy PDA automation system with 2 Pentair Laminars. SmartPool NC74S Robotic Pool Cleaner.

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879
    High PH is the problem. Chlorine is less effective at high PH. Get the PH down right away and then shock the pool.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. Back To Top    #3

    Join Date
    Oct 2007
    Location
    Parkland, FL
    Posts
    727
    okay, so I was wondering about that, I know its less effective, but is it REALLY that much less effective?
    8000 gal diamond brite pool with 650 gal spillover spa, Pentair 3hp VS pump. Jandy Cartridge filter and Jandy Heat Pump. Jandy PDA automation system with 2 Pentair Laminars. SmartPool NC74S Robotic Pool Cleaner.

  4. Back To Top    #4

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,077
    Rob,

    You have algae.......yes, it's less effective....That much!

    Rob, What happened to your pH? How did it get so high?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  5. Back To Top    #5

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,082
    If your measured numbers are correct, then the saturation index was over +1.0 with a significant chance of scaling and in particular the SWG cell may have become less efficient with too much scale.

    CYA acts as a chlorine (hypochlorous acid) buffer so moderates the effect of pH on its effectiveness. At a pH of 8.5, a pool with 5 ppm FC and 40 ppm CYA has a chlorine equivalent to a pool with a pH of 7.5 and 4 ppm FC (with the same 40 ppm CYA) so at least in theory the pH alone may not be the problem (unless there is something new to understand about algae growth in these conditions). Nevertheless, you don't want the pH to be that high and should add acid to lower it.

    How certain are you of the numbers you are measuring? Are you using a TF100 or Taylor K-2006 test kit? How did you measure a pH above 8.0 or 8.2 since these test kits only go up to that value? Also, what kind of algae is it? Is it free-floating green algae or is it yellow/mustard algae that looks like yellow/orange dirt and grows in shady areas?

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  6. Back To Top    #6

    Join Date
    Oct 2007
    Location
    Parkland, FL
    Posts
    727
    I guess it was about 8.2 then. It was at the top of the scale. In florida where I am, if you don't touch the ph, it just goes up and up and up. I didn't have acid for awhile and was busy and one thing led to another and it went without acid for awhile. I just recently put the acid back in.

    Its greenish algae right on the walls. I plan to put in bleach and kill the algae off as before, but its disconcerting that the algae came back. If its just because the PH got too high, I can fix that. But if it isn't, I'd like to figure out what caused it.

    My FC was around 5ppm the last time I measured it. Usually it would hover around 3ppm with the normal setting of the SWG. I had turned it up alittle when I noticed the Algae.
    8000 gal diamond brite pool with 650 gal spillover spa, Pentair 3hp VS pump. Jandy Cartridge filter and Jandy Heat Pump. Jandy PDA automation system with 2 Pentair Laminars. SmartPool NC74S Robotic Pool Cleaner.

  7. Back To Top    #7

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,082
    If it was maxed out at 8.2, then it could have been above. I doubt it was above 8.5 since then you'd be at equilibrium with carbon dioxide in the air vs. the water so no more would outgas. The SWG produces hydrogen gas bubbles and these outgas carbon dioxide (and a small amount of chlorine) and that causes the pH to rise.

    At a pH of 8.2-8.5 and with the other numbers you had and an FC of 3.0, then that's a hypochlorous acid concentration of 0.025 which is below the minimum required for manually dosed pools which is around 0.03. Usually with an SWG pool, you can get away with a somewhat lower chlorine level, but that is only for killing free-floating algae and in your case it sounds like you've got algae stuck on walls so obviously they don't make their way to the SWG cell to get superchlorinated. At least things are now starting to make more sense. I'll bet you don't regularly (weekly or so) brush your pool. Regular brushing probably let's those with SWG pools get away with lower chlorine levels since free-floating algae would get super-chlorinated in the SWG cell.

    So your pool probably has decent nutrients for algae so going below the Minimum is a problem for your pool. Though the minimum at 40 ppm CYA is 2.9 ppm FC, that's at a pH of 7.5. I would say that you should not only keep a watch on your pH, but also target a somewhat higher FC of around 4 ppm FC at your 40 ppm CYA level. That should keep the algae from growing even if the pH rose somewhat.

    If you ever get a water test to find out the phosphate level of your pool, that would be good information to let us know -- not that you need to do anything about it, but since your pool is behaving near the "edge" of the minimum FC level, it would be nice to know roughly what phosphate level that is. We currently think the level where the minimum FC starts to not work is around the neighborhood of 3000 ppb so info from your pool would help validate this theory of algae growth.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  8. Back To Top    #8

    Join Date
    Oct 2007
    Location
    Parkland, FL
    Posts
    727
    okay, I should mention, the SWG I use is contained in a robotic pool cleaner such as an aquabot. Its a prototype, but the real production unit I understand will be in stores like Leslies and pinch a penny in the next couple of months or so. So it basically chlorinates through the robot as it moves around the pool, since the robot cannot get in the jacuzzi, it would make sense that the algae is most prevalent over there. The jacuzzi has a spillover so the water is going through there.

    I am doing the test with the TF test kit. I have added more acid and will be working this weekend to get some bleach or liquid chlorine in the pool to get rid of the algae.
    8000 gal diamond brite pool with 650 gal spillover spa, Pentair 3hp VS pump. Jandy Cartridge filter and Jandy Heat Pump. Jandy PDA automation system with 2 Pentair Laminars. SmartPool NC74S Robotic Pool Cleaner.

  9. Back To Top    #9
    SeanB's Avatar
    Join Date
    Mar 2007
    Location
    Missouri City (suburb of Houston, TX)
    Posts
    2,622
    Nothing to add other than you can't just 'set it and forget it' when it comes to pool care.

    Just a few minutes a day several times a week will keep you on top of things.

    In the end, you give up a lot more time trying to fix problems that could have been avoided.

    Not picking on you, we're all guilty of being laxed from time to time - just a reminder.
    TFP Founder

    My Pool: 13K gal IG gunite with 7' spa, Pentair Cartridge Filter, Intellichlor IC40 SWG, Polaris 280 Cleaner, TF-100 Test Kit w/ salt test.

  10. Back To Top    #10

    Join Date
    Oct 2007
    Location
    Parkland, FL
    Posts
    727
    yep, running out of the acid didn't help for sure.
    8000 gal diamond brite pool with 650 gal spillover spa, Pentair 3hp VS pump. Jandy Cartridge filter and Jandy Heat Pump. Jandy PDA automation system with 2 Pentair Laminars. SmartPool NC74S Robotic Pool Cleaner.

  11. Back To Top    #11

    Join Date
    Oct 2007
    Location
    Parkland, FL
    Posts
    727
    question, is it important to only add enough to get to shock level of the liquid chlorine or can I just dump a ton in to raise my shock like to like 150 and let it sit for a few days till it kills the algae?
    8000 gal diamond brite pool with 650 gal spillover spa, Pentair 3hp VS pump. Jandy Cartridge filter and Jandy Heat Pump. Jandy PDA automation system with 2 Pentair Laminars. SmartPool NC74S Robotic Pool Cleaner.

  12. Back To Top    #12
    SeanB's Avatar
    Join Date
    Mar 2007
    Location
    Missouri City (suburb of Houston, TX)
    Posts
    2,622
    Why not just follow the normal steps? Sure, it may take a couple of days, but it will also have the advantage of getting you in the habit of checking your pool on a regular basis so you can prevent this from occurring again.

    Instead of looking for a quick fix, work on being consistent with your pool care.
    TFP Founder

    My Pool: 13K gal IG gunite with 7' spa, Pentair Cartridge Filter, Intellichlor IC40 SWG, Polaris 280 Cleaner, TF-100 Test Kit w/ salt test.

  13. Back To Top    #13

    Join Date
    Oct 2007
    Location
    Parkland, FL
    Posts
    727
    right, was just wondering if there was a difference. Running low on the chemicals to check as well. That chlorine test goes quick when you are using 50 drops or more at a time.
    8000 gal diamond brite pool with 650 gal spillover spa, Pentair 3hp VS pump. Jandy Cartridge filter and Jandy Heat Pump. Jandy PDA automation system with 2 Pentair Laminars. SmartPool NC74S Robotic Pool Cleaner.

  14. Back To Top    #14
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879
    With a plaster pool you can shock to a higher levels than is normally recommended, but I wouldn't go up to 150 ppm or anything like that. At very high FC levels, particularly with salt in the pool, there can start to be fairly rapid corrosion of metal touching the water. If CYA is really and truly zero you should not go over FC of 5. If CYA reads zero but there has been CYA in the pool before then 15 to 20. With measurable CYA levels then double the normal shock level for the CYA level should be alright for a few of days.

    You said your CYA level was 40, so I wouldn't shock to anything higher than 30.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

Posting Permissions

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