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Thread: Algae, but holding chlorine

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    Algae, but holding chlorine

    FC - 9
    PH - 7.6
    CYA - 95

    A few days ago I started to notice some green stuff in the corners of my crystal clear pool. It was most noticeable near the filter area. I brushed it and today it is back again. I just put in enough bleach to bring me up to a 12 and brushed the corners and sides again. My CC was .5 and I've been losing approximately 3 ppm of chlorine on sunny days. Should I take a wait and see approach or should I just go for the SLAM?

    And, yes, I know my CYA is high (former tablet user, just switched to BBB method at end of last season) but the hubby is against draining almost half the pool and refilling. He doesn't want to wait for the water to warm up again. I just keep the FC level toward the high end of what is needed
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Mod Squad tim5055's Avatar
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    Re: Algae, but holding chlorine

    Well, your target FC is 12, so you are well below that. Your minimum FC is 7, and while you are above that on sunny days you can probably drift down to it easily when you say you loose approximately 3 ppm per day. A few days with too little FC allows the algae to get a foothold, then even when you add you never get the FC high enough long enough to eradicate it.

    I would ask how you came up with CYA 95? Using a recommended test kit there are only even numbers; 60 - 70 - 80 - 90 - 100. If you are at or near 100, you may need to do a dilution CYA test as that is the upper limit of the test. Mix pool water and tap water then test the mixture.
    Here is a great chart by JamesW to identify the multiplier.

    Pool water......Tap or distilled water.........Multiply result by

    ....1...................1................................2
    ....1...................2................................3
    ....1...................4................................5

    My guess is that your CYA is much higher than you think, thus you have too little FC to combat the algae. But, that is just a guess.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Algae, but holding chlorine

    Visible algae = SLAM process.

    You should verify the CYA first , tho. ^^^
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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    Re: Algae, but holding chlorine

    CYA I got 95 because my friend couldn't see the dot at 100, but I felt I still could and got to 90, so I split the difference. It was a little iffy.
    Didn't realize my target was 12. I always bring it up to there or 12.5 everyday. I've never measured below 7.
    With that being said, it still seems like SLAMing is the way to go
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Re: Algae, but holding chlorine

    Quote Originally Posted by Betty99 View Post
    With that being said, it still seems like SLAMing is the way to go
    If you have algae, yup SLAM away
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Algae, but holding chlorine

    Oh, and thank you both very much. I have to reorder the CYA reagent, but I did start the SLAMing process under the assumption that my CYA is at 100.
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Re: Algae, but holding chlorine

    So, I brought the FC up to my SLAM level. I didn't have any FC loss overnight and no CCs. With FC at 25.5, is it OK to swim? I did a search through the forum and it seems that it is OK, but I just want to verify that that is true for my SLAM level.
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Re: Algae, but holding chlorine

    I'm confused? When did you bring it up to SLAM level of 39 if you are at 25.5 now? With your CYA of 100, it is safe to swim up to SLAM level.

    I'm surprised that with visible algae you had no loss with a Overnight FC Loss Test (OCLT).
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Algae, but holding chlorine

    According to the pool calculator, my shock level is 25 with CYA of 100. Would my shock level be different because I have visible algae?
    Another thing may be that it was not algae. I have a couple of large maples hanging over the pool. I do still believe it was algae because, like regular sediment usually does, it did not move when I swept my net over it. I was only able to remove it from the few spots that I found it by brushing. It really was a very small amount that was mostly by the filter inlet and return.
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Re: Algae, but holding chlorine

    Quote Originally Posted by Betty99 View Post
    According to the pool calculator, my shock level is 25 with CYA of 100. Would my shock level be different because I have visible algae?
    Another thing may be that it was not algae. I have a couple of large maples hanging over the pool. I do still believe it was algae because, like regular sediment usually does, it did not move when I swept my net over it. I was only able to remove it from the few spots that I found it by brushing. It really was a very small amount that was mostly by the filter inlet and return.
    Are you using the Pool Math link at the top of this page? Both it and the Chlorine/CYA chart show 39 as the shock level for 100 CYA.

    But, back to the question at hand. Yes it's safe to swim at 25.5 with CYA 100

    Now, last night after the sun was off the pool it was 25.5 and then again this morning? If yes and the water is clear and no CC then I would say it was the shortest SLAM in history.

    With 100 CYA target 12 FC and never let it go below 7. I remember these numbers well because I sat at 100 CYA for a while.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Algae, but holding chlorine

    I too was surprised, yet very happy, that I passed the OCLT. Just to confirm that I have been measuring correctly, I used the 10mL sample, added the 2 dippers of DPD powder, dissolved it, then I counted 51 drops until the pink color disappeared. I did the exact same thing last night and this morning.
    Now, I have to check on that pool math link. Why does the pool calculator tell me 25? Is there something wrong with the calculator?
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Re: Algae, but holding chlorine

    I too was surprised, yet very happy, that I passed the OCLT. Just to confirm that I have been measuring correctly, I used the 10mL sample, added the 2 dippers of DPD powder, dissolved it, then I counted 51 drops until the pink color disappeared. I did the exact same thing last night and this morning.
    Now, I have to check on that pool math link. Why does the pool calculator tell me 25? Is there something wrong with the calculator?
    Just checked it out. I've been using poolcalculator.com. The only difference I have found is the shock level, which you have pointed out to me. I will be using the PoolMath chart from now on.
    With that, since I didn't have any overnight loss, do you think I need to bother bringing FC up to 39 at this point?

    - - - Updated - - -

    Just did a double check and even with the suggested goal levels set to come from Troublefreepool.com on both the PoolMath and Poolcalulator charts, I get the two different shock goals. Weird
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Re: Algae, but holding chlorine

    PoolMath is more up to date with our current recommendations, pool calculator had been abandoned by its owner for the longest period of time.
    Did you add one more drop when the pink disappeared?

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    Re: Algae, but holding chlorine

    Yes, but it had already disappeared at 51. Do YOU think I should take it up to 39 at this point?
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Re: Algae, but holding chlorine

    Quote Originally Posted by Betty99 View Post
    Yes, but it had already disappeared at 51. Do YOU think I should take it up to 39 at this point?
    With a OCLT pass, 0 CC & clear pool I think it's time to swim!
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Algae, but holding chlorine

    Just took a quick dip with the kids!
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Re: Algae, but holding chlorine

    Betty, just curious how long you run your pump ??? Crystal clear water with algae forming could mean you are NOT running your pump enough. I just went through a similar scenario and I extended my pump run time as suggested by a good friend. It worked!!! Good luck and enjoy.
    20X36 IG vinyl (18,000 gal), 3 sheer descents, Max-Flo 1.5hp VS 2300, Aquarite T15 SWG, C3030 filter, 250,000 BTU heater, Sharkvac XL (Hayward equip)

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    Re: Algae, but holding chlorine

    Just got the stuff to retest my CYA. Apparently, it's at a 60. That's probably why the shock of 25 worked. Guess the refilling and draining that has been going on between the rain and, alternatively, the evaporation, it got there.

    - - - Updated - - -

    How long do you run it? I alternate between 4 - 8 hours and sometimes even longer if I forget to shut it. I don't put it on a timer because I like to empty the basket when I shut it off and I know I would get lazy about it if it shut off on its own.
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Re: Algae, but holding chlorine

    Still getting the little bits of what I think are algae in the recesses of my pool floor. Also, I used to have that jewel like sparkle to my water and it's kind of gone. My husband thinks I'm crazy and says that the pool is crystal clear, but I know it doesn't look quite the same, although he did comment about the fact that the water had lost some of its softness. Sooooooo confused!
    Chemicals seem to be ok.
    FC: 9.5
    CC: 0
    PH: 7.8
    ALK: 120

    You could see what happened the first time I SLAMed by reading my previous posts on this thread.

    - - - Updated - - -

    Oh and my CYA is 60
    10k gal, AG, cartridge filter, installed August 2012, Taylor K-2006

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    Re: Algae, but holding chlorine

    I am having the same problem with my water. My husband thinks I am imagining algae since I have spent so much time on here. He thinks the pool looks great and I think it's missing the sparkle I had a couple weeks ago, and what I think is algae he thinks is dirt. I am not losing FC like crazy so I am just checking it twice a day.
    22k gallons AG 30ft round, Hayward 2 speed 2hp motor, cartridge filter, Aquabot Rover Jr, Sunheater solar heater.

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