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Thread: Persistent Pool Algae - Time To Drain?

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    Unhappy Persistent Pool Algae - Time To Drain?

    Hello!

    I've been lurking for a while but decided it was time to join and ask a few questions. Let me provide some background:

    Last year I had a plaster pool that was from the 1970s and didn't look like it had never been redone. I hired a local pool contractor (big mistake, long story.. but for another thread) to remodel the entire pool. That included new tile line, new pebble finish, new skimmer, all new plumbing including new returns, dedicated suction line for pool vac, new Pentair Quad DE 60 filter, and Intelliflo VS pump. Everything is brand spankin new. The pool was finished towards the end of summer last year and I didn't really have a chance to use it before the winter.

    Start-up right off the bat with the vendor was a mess. Pool ran for 2 weeks and was getting more cloudy each day. I called the vendor and complained but they told me that was normal, but after the end of the second week I decided to look in to it myself. I popped the lid to the Quad DE and found that it didn't have any DE in it. Alas, it had just been running without DE since the day it was started up. I picked up a box of DE and charged it (6 scoops) through the skimmer and within a day or two it was sparking clean.

    Right about then I discovered TFP and I also ordered a TF100 test kit from the site here and began testing the pool. After start up most of the numbers seemed good but the CYA was at 100 which seemed quite high to me. But in any case, throughout the winter the pool didn't have any issues and ran great and was almost always clear. I switched from puck chlorine tablets to liquid chlorine in an attempt to get the CYA to come down with regular back washing and have been using just plain liquid chlorine, muratic acid, and baking soda to care for the pool.

    But now that summer has come around I am having a terrible time keeping the pool clean. A few weeks ago I went out of town for a few days and came back to find alage on the walls. It wasn't a swamp, the water was still clear and I could see the bottom everywhere perfectly - but it was clear that algae was growing on the walls. I shocked it a few times and jumped in the pool to brush the heck out of it. It would eventually go away, and a few days return again. Even with a FC reading of 5+ I would still have chlorine coming back regularly which has been getting frustrating. I would burn through 2-3ppm of FC in 24-36hours even with my CYA as high as it is.

    I tore down the filter two weeks ago and hosed and scrubbed them until they were crystal clean and recharged the filter. Right now the pump is running at 2200RPM for 6hrs and 2400rpm for 2hrs (8hr total runtime).

    This morning I tested to find a FC of 2.5 (was 6 36hrs ago) and a TC of 3.0 and algae back on the walls! Again, not a swamp - but just nuisance algae on the walls.

    I'm thinking that the CYA was too high from the start and that I'm at a point of needing to drain some water from the pool to get it under control. My CH also seems to be quite high.

    Here are my test results from today:

    Water Temp: 90
    TDS: 1650 (Non-Salt)
    FC: 13.0 (Just shocked using 2lbs dichloro 55% chlorine shock "Leslies Chlor Brite" 1hr ago)
    TC: 13.5
    CYA: 80
    pH: 7.2
    TA: 80
    CH: 610 (Yes, 50ish drops to purple and another 11 until I consider it blue)
    Tested tap water to see what it registered at here in Phoenix and I found it to be 280 (22 to purple and 28 to blue)

    I've brushed it three times today and the walls are starting to clean up nicely, but always seem to have a tinge of green to them. Just want to get this baby back to sparking clean and to stop chasing my tail! What should I be doing next? Help!

    Thanks,

    Jason

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    Re: Persistent Pool Algae - Time To Drain?

    Not sure, but a loss of 3 in the sun and a water temp of 90 doesn't seem excessive to me. Have you done an overnight loss test yet? If you see green, a SLAM would be a good idea.
    26' X 52" Intex Ultra Frame. Intex Sand Filter
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    Richard320's Avatar
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    Re: Persistent Pool Algae - Time To Drain?

    You're on the right track. Lowering CYA is a good first step.

    Then you need to run the Shock Level And Maintain process to its completion. What you are describing sounds like the M was missing.

    High CH will always be a battle for you. Just keep TA down in the area of 70 and check the CSI when you plug numbers into poolmath. As long as you stay below .6 things should be fine.
    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!

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    Re: Persistent Pool Algae - Time To Drain?

    I've always been targeting a FC of 3.0-5.0, but per the CYA/FC chart that would appear to be too low. Sounds like I should do a partial drain and refill to bring CYA down to 30-50 and then a 4-6ppm FC should keep it happy?

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    Richard320's Avatar
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    Re: Persistent Pool Algae - Time To Drain?

    Quote Originally Posted by AZJason View Post
    I've always been targeting a FC of 3.0-5.0, but per the CYA/FC chart that would appear to be too low. Sounds like I should do a partial drain and refill to bring CYA down to 30-50 and then a 4-6ppm FC should keep it happy?
    In Arizona, 50 is more realistic. In which case, the FC should never get below 4. You'll need to track things so you make sure you target high enough FC so that it doesn't dip below 4 before your next addition.
    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!

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    Re: Persistent Pool Algae - Time To Drain?

    Thanks. The pool has been plumbed for a Pentair IC40 but has had the bypass cell installed for now while I have been caring for it with liquid chlorine and acid. Since my CYA is already in the 70-80 range and I was planning to cut over to salt at some point, it would appear to make more sense to go ahead and pull the trigger on installing the cell rather than draining the water the lower the CYA now if I know the plan was to convert to salt anyhow.

    I brought the FC up to 30 last night per the SLAM process and CYA/FC charts. Forgot to re-test it this AM but just tested it again tonight 24 hrs later and I see the FC has dropped from 30 to 16.5. Pool water is looking much clearer, but there still seems to be a tiny tinge of green on the walls though nothing is coming off when brushing that I can see. Should I bring the FC back up to 30 again and re-test in the AM to see if it holds? A drop from 30 to 16.5 seems to be quite big!

    PH is now at 7.9 (aerator was left on, pool is 91 degrees!) - so I just added some acid to bring it back down.

    Thanks!

    *EDIT*

    Sorry, results:

    Water Temp: 91
    TDS: 1640 (Non-Salt)
    FC: 16.5 (was 30 24hrs ago)
    TC: 17.0
    CYA: 80
    pH: 7.9
    TA: 90
    CH: 610

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    Richard320's Avatar
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    Re: Persistent Pool Algae - Time To Drain?

    You need to run the Shock Level And Maintain process to its completion. What you are describing sounds like the M is still missing.
    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!

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    Mod Squad jblizzle's Avatar
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    Re: Persistent Pool Algae - Time To Drain?

    Yes raise the FC back up..once you pass the 3 criteria to stop the SLAM process, then you can get the SWG back up.

    You can not test the pH when the FC is above 10ppm.
    Jason, TFP Moderator
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    Re: Persistent Pool Algae - Time To Drain?

    Try to test more frequently.
    26' X 52" Intex Ultra Frame. Intex Sand Filter
    26' X 52 Intex Ultra Frame Install
    You can lead a horse to (clear) water, but you can't force him to swim in it!

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