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Thread: Black Algae in a vinyl pool?

  1. #1
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    Black Algae in a vinyl pool?

    Is it possible to get black algae in a vinyl pool?? I have a few small areas of black stains on the wall of the deep end. If so do same rules to clear up apply as on a plaster pool??

    38,000 gal IG vinyl
    Mainly liquid bleach for cl
    some pucks used during vacation and off and on through the season
    have had issues of 0 cya upon opening the pool.

    right now
    CYA - 30
    FC - 10
    CC - .5
    PH - 7.4
    TA - 100
    38,000 gal IG Vinyl
    Hayward Northstar SP4015X20 2hp uprated pump
    Pentair TRITON II TR100 Sand filter

  2. #2
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    Re: Black Algae in a vinyl pool?

    Not usually. Have you done a FC overnight test to see if your FC is holding?

    Try rubbing a trichlor puck on the stains, and see if they fade. Do they brush away easily?

    CYA going to 0 was discussed on the other thread, Black Algae would not account for that.

    Take a look at this....Do your stains look this way? Black Algae have a tough outer shell and roots that are resistant to chlorine. The way to rid your pool of Black Algae is holding your FC at shock level and frequent brushing. In a plaster pool you would use a SS brush (not new plaster) in a vinyl pool you use a brush that is safe for vinyl liners.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  3. #3
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    Re: Black Algae in a vinyl pool?

    It does not look like the pics I have seen and in your reply. It is more in a line in stead of the dots. It does seem to go away at the higher cl levels but comes back quickly (within a day if the levels drift to 1). It does not brush off at all. Brushing once a day does seem to help when the cl levels are at shock numbers.

    Working on an FC overnight test tonight to see how it holds.
    38,000 gal IG Vinyl
    Hayward Northstar SP4015X20 2hp uprated pump
    Pentair TRITON II TR100 Sand filter

  4. #4
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    Re: Black Algae in a vinyl pool?

    Raised the FC from 10 to 12 @ 10:00pm last night. This morning @ 6:30 the FC was down to 9.5 and the TC was .5. I did get about .25" of rain over night so I don't know how this will skew the numbers.

    Here is a break down of the chain of events from the opening.
    Day 1 - pulled off the cover to a fairly clear pool. Did have a few oak tree leaves in the deep end. No more the about 20. Did have some dirt on the bottom as well. Fired up the pump and dropped in the dolphin robot cleaner to clean up the silt on the bottom. Tested water.

    FC - 0
    TC - 0
    PH - 7.4
    TA - 100
    CYA - 0

    Dumped in 786oz of 6% liquid cl. Thought I should get up to about 9 or so on the FC. Only hit about 4-4.5.
    Four hours later down to 0. Added another 384oz lc and got up to 4. In goes 8 pounds of CYA in hopes of seeing around 30ppm.

    Day 2 - Checked the next morning 0 again so in goes another 384oz and it goes to 0 by end of the day. CYA did make it to 20-25.

    Day 3 - Read a little on the board about disappearing CYA and realized that I may have a bigger issue on my hands. Dumped in 5lbs of 49% cal-hypo and made it up to 10 FC and .5 TC. two hours later down to 9 and .5 TC. Poured in 384oz 6% lc in hopes to push up to 12-14 over night. Tested an hour later and up to 12.

    Day 4 - (This morning) FC 9.5 TC .5 CYA looks to be about 20-25. I did get about .25" of rain so I don't know how much this effects the CL levels. Planning on going home @ lunch and check all the numbers to see where things have ended up. Tonight I plan on adding 4lbs of CYA in hope of hitting 30-40.

    The whole time the water have gone from just a little cloudy (see the main drain in the deep end fairly good) to very cloudy (barely see the drain) and back to pretty clear (still a little cloud but able to see the pattern in the floor. There has been what looks to be some dark (black??) stains in a few places on the wall in the deep end. Not really spots but more like lines. These seem to have lightened a bunch with the higer cl levels and hitting with a brush every couple of hours. They seem to still be there but getting lighter.

    Will post all number at lunch. Wondering how long it would be recommended that I keep the CL up and in this case how high should I be trying to hold it.

    Michael Julian
    38,000 gal IG Vinyl
    Hayward Northstar SP4015X20 2hp uprated pump
    Pentair TRITON II TR100 Sand filter
    38,000 gal IG Vinyl
    Hayward Northstar SP4015X20 2hp uprated pump
    Pentair TRITON II TR100 Sand filter

  5. #5
    Administrator JasonLion's Avatar
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    Re: Black Algae in a vinyl pool?

    I really don't think that you have black algae. Black algae is almost unheard of in vinyl liner pools. Your marks sound like organic stains that will fade away slowly as long as you keep chlorine in the pool.

    As long as you are losing FC overnight you still have something organic in the water that needs to be taken care of, so you should continue shocking.

    If CYA is currently at 25, then you want to maintain FC around 10. If you add another 4 lbs of CYA, then you should try to keep FC up around 14 or 15.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  6. #6
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    Re: Black Algae in a vinyl pool?

    I agree with Jason, it didn't sound like Black Algae. BTW, I learned the hard way. I was told 5 years ago I had BA and for 2 subsequent seasons repeatedly tried the "black algae" treatment the Pool Store sold me, which involved shocking the pool and adding this granule stuff, and lots of backbreaking brushing. So when the water was up to shock the stains would disappear so we thought "great, it worked, must have been the BA remover." But as soon as the FC dropped to "normal" the stains would return. So we'd repeat the process, per the PS advice....same thing. Here's an old pic from my first month on TFP where I mentioned these stains.

    Finally, after following the advice of TFP guru's for several months, the stains eventually faded and they never came back. Turns out my CYA was too high and I never had enough FC to keep them away. IT was so simple...
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  7. #7
    Mod Squad JohnT's Avatar
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    Re: Black Algae in a vinyl pool?

    Quote Originally Posted by frustratedpoolmom
    I was told 5 years ago I had BA and for 2 subsequent seasons repeatedly tried the "black algae" treatment the Pool Store sold me, ......
    Finally, after following the advice of TFP guru's for several months, the stains eventually faded and they never came back. Turns out my CYA was too high and I never had enough FC to keep them away. IT was so simple...
    Wow, you must have been..........Frustrated...
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  8. #8
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    Re: Black Algae in a vinyl pool?

    Quote Originally Posted by JohnT
    Wow, you must have been..........Frustrated...
    Ya think?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  9. #9
    Senior Member chris4150's Avatar
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    Re: Black Algae in a vinyl pool?

    Didnt the "Frog" play into it, or was the "Frog" the source of the high CYA?
    13,500 gallon free form Pebble Tec pool- 2 skimmers
    Pentair Intelli-Flow filter pump, Pentair Intelli-Super Flo booster pump, waterfall pump, Del Ozone Eclipse 1 generator, Pentair Clean & Clear Plus Cartridge filtration, Nature 2 XG Clear Vision, In-line Chlorinator, Polaris 280, Raypack heater, and Color Logic LED lights.

    Proud user of BBB, pool school, pool calculator, TF-100, and the advice of the friendly people here!

  10. #10
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    Re: Black Algae in a vinyl pool?

    Quote Originally Posted by frustratedpoolmom
    Here's an old pic from my first month on TFP where I mentioned these stains.
    WOW!! How did you get a pic from the bottom of my pool??? That is exactly what it looks like only a bit smaller area on the floor. The wall is a bit darker and in a small jagged line about 6"-8" long and .25" wide in two different areas.

    Looking at things over lunch, the stains have all but gone. Dropped from 9.5 to 8 in 5 hours. It did rain again a very small amount in the time.

    Overall numbers
    FC - 8
    TC - 0
    PH - 7.3
    TA - 100
    CYA - 20

    I did not add anything to the water. I plan to add enough LC to get the FC up to 12 tonight and then do another morning check to see if I am still dropping. What would be an acceptable drop??

    I do have a question about CH. I very rarely check it as I have been told by people on a different board that it is not too critical in vinyl pools. It has always stayed in the 250 to 320 range. I checked it for the first time this season today and it came up in the high 300's. About 380. Is this a concern? Is a partial drain the only way to lower the number?

    I have had this pool for 7 seasons and been using the BBB method since the get go. I purchased Ben's test kit from Pool Solutions when I got started. This is the first year that I have really had any tough issues. I was running a WaterMaid SWG up until the middle of last year. The venturi finely gave up the ghost in July and I never replaced it.

    Anyway thanks for all the great advice...
    38,000 gal IG Vinyl
    Hayward Northstar SP4015X20 2hp uprated pump
    Pentair TRITON II TR100 Sand filter

  11. #11
    Senior Member chris4150's Avatar
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    Re: Black Algae in a vinyl pool?

    msjulian,

    what city and state do you live in?
    13,500 gallon free form Pebble Tec pool- 2 skimmers
    Pentair Intelli-Flow filter pump, Pentair Intelli-Super Flo booster pump, waterfall pump, Del Ozone Eclipse 1 generator, Pentair Clean & Clear Plus Cartridge filtration, Nature 2 XG Clear Vision, In-line Chlorinator, Polaris 280, Raypack heater, and Color Logic LED lights.

    Proud user of BBB, pool school, pool calculator, TF-100, and the advice of the friendly people here!

  12. #12
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    Re: Black Algae in a vinyl pool?

    Quote Originally Posted by chris4150
    Didnt the "Frog" play into it, or was the "Frog" the source of the high CYA?
    Indirectly, the Frog played arole but the stains were definetly organic because they faded from shocking.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  13. #13
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    Re: Black Algae in a vinyl pool?

    Quote Originally Posted by msjulian
    What would be an acceptable drop??

    I do have a question about CH. I very rarely check it as I have been told by people on a different board that it is not too critical in vinyl pools. It has always stayed in the 250 to 320 range. I checked it for the first time this season today and it came up in the high 300's. About 380. Is this a concern? Is a partial drain the only way to lower the number?
    Your FC should hold overnight, meaning you lose less than 1ppm. Glad the stains are fading. Keeping your FC up to your target for a few months should keep them away permanently.

    Calcium is irrelevant to a vinyl liner, 50 is even acceptable. Don't worry too much about the calcium, though its high, as long as you keep your PH under 7.8 it shouldn't be a problem. Yes, draining is really the only practical way to lower it. Is your fill water high in calcium? Have you tested your fill water?

    You do have a fresh test kit, right?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  14. #14
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    Re: Black Algae in a vinyl pool?

    I live in Newburgh Indiana. Still a bit cool to swim but getting close.

    Do I need to keep it @ the 10-12 range for a couple of months??

    I usually buy enough reagents to get through the year. I get my refills form recsupply. Seem to be the cheapest overall that I have found for Taylor reagents. What is the normal shelf life of most reagents if kept in a dark, cool cabinet??
    38,000 gal IG Vinyl
    Hayward Northstar SP4015X20 2hp uprated pump
    Pentair TRITON II TR100 Sand filter

  15. #15
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    Re: Black Algae in a vinyl pool?

    Quote Originally Posted by msjulian
    I live in Newburgh Indiana. Still a bit cool to swim but getting close.

    Do I need to keep it @ the 10-12 range for a couple of months??

    I usually buy enough reagents to get through the year. I get my refills form recsupply. Seem to be the cheapest overall that I have found for Taylor reagents. What is the normal shelf life of most reagents if kept in a dark, cool cabinet??
    I was thinking a range of 6-8 for your CYA of 20, is it? No need to keep the FC that high. Is your 20 by choice or are you planning to adjust it up?

    dark, cool = 1-2 years I believe.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  16. #16
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    Re: Black Algae in a vinyl pool?

    Planning on adjusting up to the 30 range. After reading the posts about the CYA eating bacteria I wanted to make sure I had it killed off before I started to raise it again. I didn't want to keep feeding the monster....

    So now my plan is to get the pool up to 30ppm CYA and hold it at the 8-10 range for the first few months to completely rid the pool of the organic stains. (boy that's going to be a lot of CL)
    38,000 gal IG Vinyl
    Hayward Northstar SP4015X20 2hp uprated pump
    Pentair TRITON II TR100 Sand filter

  17. #17
    Senior Member chris4150's Avatar
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    Re: Black Algae in a vinyl pool?

    msjulian,

    thats ok, Im in the same situation as you are, I just discovered that my stains react to trichlor tabs, so now Im in the process of trying to rid the stains with continuous higher levels of FC.
    13,500 gallon free form Pebble Tec pool- 2 skimmers
    Pentair Intelli-Flow filter pump, Pentair Intelli-Super Flo booster pump, waterfall pump, Del Ozone Eclipse 1 generator, Pentair Clean & Clear Plus Cartridge filtration, Nature 2 XG Clear Vision, In-line Chlorinator, Polaris 280, Raypack heater, and Color Logic LED lights.

    Proud user of BBB, pool school, pool calculator, TF-100, and the advice of the friendly people here!

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