Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 10 of 10

Thread: Chlorine Resistant Algae?

  1. Back To Top    #1

    Join Date
    Jun 2015
    Location
    Apple Valley, CA
    Posts
    10

    Chlorine Resistant Algae?

    I've gone and done the unthinkable; did a complete drain and refill of my AG pool in a drought area. I've had it fighting a constantly green pool. Especially when I don't fully understand why algae loves my pool so much. Here are my chemistry results while I had a green pool and before I lost my patience and drained it.

    FC: 38
    CC: .5
    pH: 7.6
    CH: 62 (sort of irrelevant since I have an AG pool)
    TA: 162
    CYA: 180

    Even with the above results, the algae was having a party in there; alive and well and a beautiful shade of green. I know a large part of the problem is my high CYA level. It's an unavoidable consequence of using di-chlor tablets over time. Two weeks ago I had my house painted and forgot about my pool for 4-5 days and naturally it was a swamp. So I shocked it with 4 bags of lithium hypochlorite and the next day the green was gone and after another week of filtering I had just about cleared the cloudiness, when one day I notice dirt on the bottom with green under it. I checked the FC level and it was 14.5 and ran my pool cleaner to clean out the dirt and left for the day. When I returned, the pool was a cloudy, green mess. So I shocked it again with 5 bags of lithium to a FC of 48 and filtered all night. The next morning the pool looked exactly the same as it did the day before. That's when I lost my patience and just drained it and refilled it. According to the pool math tool, at a CYA level of 180 my FC level needs to be 14-21 with a shock level of 71. I would need at least 12 bags of lithium shock to achieve that FC level. I can't afford to be putting $100 a week worth of chlorine in there just to keep the green out. So my question is: did I do the right thing by draining and refilling to get rid of the excess CYA and then throwing away the di-chlor tablets and switching to liquid sodium hypochlorite?
    15x30 13,500 gallon AG Cameo Oval Pool. Pentair 1 1/2 hp OptiFlow pump. Pentair SD40 sand filter. Hayward 75 sqft cartridge filter. Taylor K-2006 test kit.

  2. Back To Top    #2

    In the Industry

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

    Re: Chlorine Resistant Algae?

    Is your CYA 180 now after draining? That doesn't make sense.

    Don't worry, you algae is not chlorine resistant.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  3. Back To Top    #3

    Join Date
    Jun 2015
    Location
    Apple Valley, CA
    Posts
    10

    Re: Chlorine Resistant Algae?

    No, the CYA was 180 before I drained it. I haven't checked it yet because my pool is filling as I write this.
    15x30 13,500 gallon AG Cameo Oval Pool. Pentair 1 1/2 hp OptiFlow pump. Pentair SD40 sand filter. Hayward 75 sqft cartridge filter. Taylor K-2006 test kit.

  4. Back To Top    #4

    In the Industry

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

    Re: Chlorine Resistant Algae?

    I get it. I think you did the right thing.

    Until the pool gets up to the skimmers, why don't you put 1/2 gallon of Clorox in your pool this evening.

    Once your pool is filled halfway up the skimmers. Run your pump for maybe 30 minutes and then take a sample from maybe a foot deep in the pool.

    I like to take that sample inside and test sitting at a table. However you do it, please give us a complete set of test results.

    Your CYA should now be zero or so close to it you can't measure it. That not a bad thing!
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  5. Back To Top    #5

    Join Date
    Dec 2014
    Location
    Santa Ana, CA
    Posts
    523

    Re: Chlorine Resistant Algae?

    how do you measure those high level of FC? Dropping 76 drops into 10mL sample or diluting it first?

    If diluting you need to mix the sample and pour out mixture excess so it remains at the required level (10 or 25 mL). Please also test the water you use for diluting as it needs to be free of chlorine, etc. Distilled would be the best but I used my local tap water as it is sufficiently clean. When my CYA was at 300 I used this trick every time and my multiplier was 2 ppm after 1:3 dilution. Thanks to this site I never had a green mess on my hands even though CYA was off the charts.
    44k plaster pool, Pentair 011018 pump, DE6020 filter, LED lights, K2006 test kit

  6. Back To Top    #6

    Join Date
    Jun 2015
    Location
    Apple Valley, CA
    Posts
    10

    Re: Chlorine Resistant Algae?

    Quote Originally Posted by max2k View Post
    how do you measure those high level of FC? Dropping 76 drops into 10mL sample or diluting it first?
    Yes, I added a whole lotta drops. Tap water does have some chlorine in it so I didn't want to dilute with that and throw off the result. Distilled water is a good idea though. What I got so fed up with was even though the FC is at levels you probably don't want to swim in, the algae still thrives in it. I'm pretty sure the high CYA level is hindering the chlorine's affect. I've never heard of anyone having to keep their FC level at >20ppm all the time just to keep their pool clear. That's what I've been having to do.

    Duraleigh, are you referring to 1/2 gallon of household bleach or regular pool store liquid sodium hypochlorite?
    15x30 13,500 gallon AG Cameo Oval Pool. Pentair 1 1/2 hp OptiFlow pump. Pentair SD40 sand filter. Hayward 75 sqft cartridge filter. Taylor K-2006 test kit.

  7. Back To Top    #7

    Join Date
    Jun 2015
    Location
    Apple Valley, CA
    Posts
    10

    Re: Chlorine Resistant Algae?

    Finished refilling. Post fill chemistry:

    FC: 4
    CC: 0
    pH: 7.8
    TA:80
    CYA: <30 (The K-2006 CYA test only goes down to 30. I can still clearly see the black dot at 30, so I don't really know what the CYA level is)

    As I write this, pool is is sparkling clear and beautiful. I will recheck the FC later this afternoon to see how it's holding up. Any recommendations, please advise.
    15x30 13,500 gallon AG Cameo Oval Pool. Pentair 1 1/2 hp OptiFlow pump. Pentair SD40 sand filter. Hayward 75 sqft cartridge filter. Taylor K-2006 test kit.

  8. Back To Top    #8

    Join Date
    Dec 2014
    Location
    Santa Ana, CA
    Posts
    523

    Re: Chlorine Resistant Algae?

    Quote Originally Posted by mdenbow View Post
    Finished refilling. Post fill chemistry:

    FC: 4
    CC: 0
    pH: 7.8
    TA:80
    CYA: <30 (The K-2006 CYA test only goes down to 30. I can still clearly see the black dot at 30, so I don't really know what the CYA level is)

    As I write this, pool is is sparkling clear and beautiful. I will recheck the FC later this afternoon to see how it's holding up. Any recommendations, please advise.
    if the pool is under direct sunlight I'd bring CYA to 40 and maintain FC at 5- according to the chart. May be bring down pH a little- depends where it tends to go on its own. Basically, maintenance stuff- you need to perform these tests daily at the beginning to get a feeling how fast those numbers change as each pool is unique. Then once/twice a week would be enough.
    44k plaster pool, Pentair 011018 pump, DE6020 filter, LED lights, K2006 test kit

  9. Back To Top    #9

    Join Date
    Jun 2015
    Location
    Apple Valley, CA
    Posts
    10

    Re: Chlorine Resistant Algae?

    Quote Originally Posted by max2k View Post
    if the pool is under direct sunlight I'd bring CYA to 40 and maintain FC at 5- according to the chart. May be bring down pH a little- depends where it tends to go on its own. Basically, maintenance stuff- you need to perform these tests daily at the beginning to get a feeling how fast those numbers change as each pool is unique. Then once/twice a week would be enough.
    The pool is in full sun most of the day. I'm a little gun shy about adding cyanuric acid now. I'm adding a little at a time to try and sneak up on 40ppm. I threw away the di-chlor tablets I'd been using. I've been using liquid sodium hypochlorite 10% solution, keeping the FC between 3-5ppm and my pool has been beautifully crystal clear. The pH has drifted down to around 7.4-7.5. I also replaced the filter element in my Hayward cartridge filter which really helped the circulation. I guess most pool owners need to refresh their water every couple three seasons because after adding this and that to it to correct one problem or another, it eventually turns into a chemical soup that just needs to be drained and discarded. Accurate statement? Thanks for the help.
    15x30 13,500 gallon AG Cameo Oval Pool. Pentair 1 1/2 hp OptiFlow pump. Pentair SD40 sand filter. Hayward 75 sqft cartridge filter. Taylor K-2006 test kit.

  10. Back To Top    #10
    cubbybeave08's Avatar
    Join Date
    Feb 2008
    Location
    Northwest Indiana
    Posts
    890

    Re: Chlorine Resistant Algae?

    Quote Originally Posted by mdenbow View Post
    No, the CYA was 180 before I drained it. I haven't checked it yet because my pool is filling as I write this.
    That's why...i guarantee you were not putting in anywhere near enough chlorine to fight Algae at CYA of 180...if thats even accurate...

Posting Permissions

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