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Thread: Black Algae

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    Black Algae

    We have just returned from 8 months over seas and we have black algae, big time. We have about a 25,000 gal Gunite pool. I have been told the "best" way, although not the easiest way to get rid of it was to drain the pool and to either steel brush or use a pressure washer to knock the "heads" off and then to scrub it with liquid chlorine and\or tri-clor tabs until it turns "pinkish-brownish" - then do it again just to be on the safe side. Was told to add a "super-chlorinate" as we fill it up that will take the FC to about 15 PPM and that should do it. On its surface this process makes sense to me but I am not a pool expert. Honestly, at this stage, if this is "surest" way that is fine with me to get rid of it, this process is OK. This pool is in Texas.

    What are your thoughts, comments, additional advice etc?
    Location: Atlanta, Georgia.
    Pool: 15,000 gallon 32'x18', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic CoverStar solar pool cover, 3 waterfalls (not from spa).
    Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

    To my pool store owner, nothing is more important than my pool and my money.

    Richard's PoolEquations Spreadsheet

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    JasonLion's Avatar
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    Re: Black Algae

    Welcome to TFP!

    Black algae is probably the most difficult kind of algae to get rid of. Some people have had success by gently rubbing the black algae with a trichlor tablet. But if there is a lot of it that might not be practical.
    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

    Re: Black Algae

    Fill the pool in and start over.

    Just kidding. The best success I have had is to underwater pressure wash and then get the chlorine up very high for a week or so and daily brush with a combo brush (nylon/stainless bristles).

    Just be careful underwater pressure washing with which tip/PSI you use. You want to knock the heads off as efficiently as possible without damaging the plaster. Test it in an inconspicuous area and go from there.
    21' Leslies Beachland Ag Pool, 10,000 gallons, professionally installed (best money I ever spent) Hayward 16" sand filter w/Pentair two speed pump Fafco 4x20 solar heater,Aqua Trol RJ. Borates added. Hard plumbed.

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    Re: Black Algae

    Aquaman, that is a very good idea!! Do you think it would be safe to try on a liner pool? (I've 'written my name' on a few plaster pools while pressure washing them in preparation for a replaster - so realize the potential for liner damage )
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

  5. Back To Top    #5

    Re: Black Algae

    Which idea, the pressure washing or filling it in and starting over?

    Honestly I don't know about liner pools. I have no experience with them. I'm a little surprised black algae even grows in them. It's such a pain in plaster pools because the roots dig into the plaster. Do the roots go through the liner? If so, wouldn't that just ruin the liner anyway?
    21' Leslies Beachland Ag Pool, 10,000 gallons, professionally installed (best money I ever spent) Hayward 16" sand filter w/Pentair two speed pump Fafco 4x20 solar heater,Aqua Trol RJ. Borates added. Hard plumbed.

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    frustratedpoolmom's Avatar
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    Re: Black Algae

    I was told an old issue with my pool was black algea. Not for sure tho...in any event it left a permanent stain in my liner. It's not active algae, that much I do know.
    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

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    Re: Black Algae

    It seems that the roots for black algae grow through the waterproof liner!! I've replaced liners with BA and found it to be in the floor in the same areas as the spots on the liner We treat the effected areas of the floor with 12.5% liquid chlorine - sometimes it works/ sometimes it doesn't -- It's my belief that the ones that it doesn't work for aren't maintaining their FC - but my customers lie about maintaining their pools

    Thanks for the idea of using the pressurewasher to 'knock off' the heads
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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    frustratedpoolmom's Avatar
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    Re: Black Algae

    Quote Originally Posted by waste
    It seems that the roots for black algae grow through the waterproof liner!! I've replaced liners with BA and found it to be in the floor in the same areas as the spots on the liner We treat the effected areas of the floor with 12.5% liquid chlorine - sometimes it works/ sometimes it doesn't -- It's my belief that the ones that it doesn't work for aren't maintaining their FC - but my customers lie about maintaining their pools

    Thanks for the idea of using the pressurewasher to 'knock off' the heads
    Mmmhmmmm....my algae (?) grew when I was using the Frog and held the recommended 1ppm FC....
    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. Back To Top    #9

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    Re: Black Algae

    Aquaman - What do you think off the idea of draining the pool and then pressure washing and then brushing the effected areas a couple of times with liquid chlorine and then filling it up with hypo chlorinated water ? I realize it is probably overkill, alot like shooting a snake 5 times when one shot would do it - but then again, sometimes and to some people the value of a nights sleep knowing the snake is dead, dead, dead, dead is worth the cost of the extra bullets. That is the case here if it increasing the probability of a "sure kill."
    Location: Atlanta, Georgia.
    Pool: 15,000 gallon 32'x18', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic CoverStar solar pool cover, 3 waterfalls (not from spa).
    Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

    To my pool store owner, nothing is more important than my pool and my money.

    Richard's PoolEquations Spreadsheet

  10. Back To Top    #10

    Re: Black Algae

    Quote Originally Posted by AzWildcat
    Aquaman - What do you think off the idea of draining the pool and then pressure washing and then brushing the effected areas a couple of times with liquid chlorine and then filling it up with hypo chlorinated water ? I realize it is probably overkill, alot like shooting a snake 5 times when one shot would do it - but then again, sometimes and to some people the value of a nights sleep knowing the snake is dead, dead, dead, dead is worth the cost of the extra bullets. That is the case here if it increasing the probability of a "sure kill."
    Well, I'm a big fan of shooting snakes 5 times...I don't trust anything that doesn't have shoulders.

    On the pool topic, I don't think draining is going to help you much in this case. You can achieve everything you need to do underwater and you don't run the risk of floating the pool.

    What part of TX are you in?
    21' Leslies Beachland Ag Pool, 10,000 gallons, professionally installed (best money I ever spent) Hayward 16" sand filter w/Pentair two speed pump Fafco 4x20 solar heater,Aqua Trol RJ. Borates added. Hard plumbed.

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    Re: Black Algae

    Katy - which is about 30 miles west of Houston.

    OK if don't drain the pool and bust the heads using under water pressure washer, what is your plan of "full engagement" to give me the best shot of not having to hit speed dial for the concrete company. Please, don't be afraid to assume I don't know which end of the bullet goes into the breech of the gun. After all, my high IQ allowed me to agree to replacing perfectly good dirt with a breeding ground for all known water borne menaces with tenacles that attach directly to my wallet.
    Location: Atlanta, Georgia.
    Pool: 15,000 gallon 32'x18', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic CoverStar solar pool cover, 3 waterfalls (not from spa).
    Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

    To my pool store owner, nothing is more important than my pool and my money.

    Richard's PoolEquations Spreadsheet

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    Re: Black Algae

    Quote Originally Posted by AzWildcat
    Katy - which is about 30 miles west of Houston.

    OK if don't drain the pool and bust the heads using under water pressure washer, what is your plan of "full engagement" to give me the best shot of not having to hit speed dial for the concrete company. Please, don't be afraid to assume I don't know which end of the bullet goes into the breech of the gun. After all, my high IQ allowed me to agree to replacing perfectly good dirt with a breeding ground for all known water borne menaces with tenacles that attach directly to my wallet.
    1) Pressure wash.
    2) Hit the pool with a ton of bleach while keeping the pH down to 7.2...follow the Chlorine/CYA chart (Yellow Mustard Shock or higher) to determine how high in your case. chlorine-cya-chart-t2346.html
    3) Keep the chlorine high and brush it every day with a combo brush. A week should do it.
    4) Follow the chlorine/CYA chart to keep your chlorine at correct levels at all times going forward.

    "My high IQ allowed me to agree to replacing perfectly good dirt with a breeding ground for all known water borne menaces with tenacles that attach directly to my wallet."

    That is the quote of the year!

    I'm in Houston as well...in our area I would avoid draining as much as possible, even though it's been reasonably dry.
    21' Leslies Beachland Ag Pool, 10,000 gallons, professionally installed (best money I ever spent) Hayward 16" sand filter w/Pentair two speed pump Fafco 4x20 solar heater,Aqua Trol RJ. Borates added. Hard plumbed.

  13. Back To Top    #13

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    Re: Black Algae

    The key really is to brush or otherwise knock off the head of the algae since it is that protective slime layer that prevents chlorine from killing it. When not protected in that way, the order of heartiness (based on lab studies) of algae is green < black < yellow/mustard so if you get the surface layer off of the black algae then somewhat higher chlorine levels will kill it and keep it away. Using the yellow/mustard chlorine recommendations for shocking will be fine for killing it and if truly gone the normally recommended chlorine levels usually keep it away.

    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"

  14. Back To Top    #14

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    Re: Black Algae

    It is not very often I get to expose my ignorance publically so here goes:

    1) My CYA is about 85 so I thought I'd drain the pool by about 1\3 to lower the CYA, make pressure washing a little easier, and to give me a little "wiggle" room on the Chlorine/CYA chart.
    a) How do I get the knocked off heads and "algae body parts" out of the pool ?
    Regular filtration (we have a DE filter) and the Polaris ?
    b) How much time do I have before the algae starts to grow new protective heads ? It will probably take 2-3 hours (will do a test tonight) to pressure wash the whole thing & I will be in the pool doing it (yep, there is that much BA in the pool). I can wear my super-duper neopreme (sp) camo duck hunting suit as protection if you recommend washing it with a high chlorine content already in it.
    c) What kind or strength of bleach do you recommend ? I have never used bleach as a chlorinating agent.

    Well, this is kind of a strip tease. I am going to expose my ignorance slowly. The best is yet to come.

    Thanks
    Location: Atlanta, Georgia.
    Pool: 15,000 gallon 32'x18', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic CoverStar solar pool cover, 3 waterfalls (not from spa).
    Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

    To my pool store owner, nothing is more important than my pool and my money.

    Richard's PoolEquations Spreadsheet

  15. Back To Top    #15

    Re: Black Algae

    Quote Originally Posted by AzWildcat
    It is not very often I get to expose my ignorance publically so here goes:

    1) My CYA is about 85 so I thought I'd drain the pool by about 1\3 to lower the CYA, make pressure washing a little easier, and to give me a little "wiggle" room on the Chlorine/CYA chart.
    a) How do I get the knocked off heads and "algae body parts" out of the pool ?
    Regular filtration (we have a DE filter) and the Polaris ?
    b) How much time do I have before the algae starts to grow new protective heads ? It will probably take 2-3 hours (will do a test tonight) to pressure wash the whole thing & I will be in the pool doing it (yep, there is that much BA in the pool). I can wear my super-duper neopreme (sp) camo duck hunting suit as protection if you recommend washing it with a high chlorine content already in it.
    c) What kind or strength of bleach do you recommend ? I have never used bleach as a chlorinating agent.

    Well, this is kind of a strip tease. I am going to expose my ignorance slowly. The best is yet to come.

    Thanks
    1) Yes, get the CYA down and keep it down in the future by discontinuing the use of trichlor tablets.
    a) Depending on how much accumulated gunk there is after you're done you may want to vacuum. If it's not enough to really see it then your filter and polaris can handle it.
    b) Add the chlorine after you pressure wash. You don't need the duck suit. It won't grow back in 2-3 hours.
    c) Plain old unscented laundry bleach from the grocery store will work well. It's readily available as 5.5% and 6% in Houston. Either will work. Just stock up; you're going to need plenty.

    You may want to consider using bleach as your regular chlorination in the future. It's cheaper and produces better results if done correctly. Look through the "What's BBB" thread and read some of the pool school subjects.
    21' Leslies Beachland Ag Pool, 10,000 gallons, professionally installed (best money I ever spent) Hayward 16" sand filter w/Pentair two speed pump Fafco 4x20 solar heater,Aqua Trol RJ. Borates added. Hard plumbed.

  16. Back To Top    #16
    Ohm_Boy's Avatar
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    Re: Black Algae

    Warehouse Pools on Mason generally stocks 12% liquid chlorine, 4 gals per case at around 13-14 bucks, or that is what I recall from last fall.
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

  17. Back To Top    #17

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    Re: Black Algae

    OK - Read the BBB article as well as some of the threads re BBB. A whole lot of light bulbs went off. We're talking parallel universes here aren't we ? If one universe is toting around the water test bottle from the pool store you're the least mad at that month and buying what they say you need and *****ing about how expensive it is versus the other universe which is taking ownership and responsability every day, getting some education, and testing and tweaking and making adjustments with relativley inexpensive commonly available household products, then I need to be beamed over. Am assumming I will be able to just dial my Rainbow chlorinator to OFF and kiss off using pucks once I go BBB.

    Does the Liquadator work well in Texas ?

    Will order the test kit today. I do want to go to war against the BA this weekend but will not have the test kit. Suggestions as to how much bleach I might need for a 25K gallon pool and is it OK to "overkill" with bleach for a few days until I can accurately test ? I can monitor my pH and keep it in the 7.2 range with my Walt Disney autograph model test kit and muratic acid.
    Location: Atlanta, Georgia.
    Pool: 15,000 gallon 32'x18', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic CoverStar solar pool cover, 3 waterfalls (not from spa).
    Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

    To my pool store owner, nothing is more important than my pool and my money.

    Richard's PoolEquations Spreadsheet

  18. Back To Top    #18

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    Re: Black Algae

    Saw that at Warehouse. Dumb question - is liquid chlorine the same as bleach ? Realize it is twice as strong but is it absent the "additives" the trichlor pucks do ?

    Thanks
    Location: Atlanta, Georgia.
    Pool: 15,000 gallon 32'x18', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic CoverStar solar pool cover, 3 waterfalls (not from spa).
    Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

    To my pool store owner, nothing is more important than my pool and my money.

    Richard's PoolEquations Spreadsheet

  19. Back To Top    #19
    frustratedpoolmom's Avatar
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    Re: Black Algae

    Quote Originally Posted by AzWildcat
    Saw that at Warehouse. Dumb question - is liquid chlorine the same as bleach ? Realize it is twice as strong but is it absent the "additives" the trichlor pucks do ?

    Thanks
    DING DING DING DING DING - we have a winner!

    Twice as strong so use half the amount. The pool calc will allow you to change the %% so it gives you proper dosing.

    I love the parellel universe thing! LOL
    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

  20. Back To Top    #20
    Ohm_Boy's Avatar
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    Re: Black Algae

    Of all the chlorine sanitizing products you can find for your pool, all tend to have other ingredients which will change the overall chemistry of your pool except for liquid chlorine. And, just to help you keep them straight in your mind, let me recap the significant differences among the various LIQUID CHLORINE products...

    In the pool store universe, they have
    a) Liquid Chlorine. Active ingredient is Sodium Hypochlorite.
    b) Liquid "Shock", which is liquid chlorine. Active ingredient is Sodium Hypochlorite.

    Now over in the BBB universe, the favorite chlorine product is
    a) Liquid laundry bleach. Active ingredient is Sodium Hypochlorite.

    So you can easily see the difference among the products. You have to choose from Sodium Hypochlorite, Sodium Hypochlorite, or Sodium Hypochlorite. Naturally, it can be tough to get the right one.

    Seriously, the only difference in the liquid products lie in the concentrations. Generally, household bleach is 5.25% to 6% Sodium Hypochlorite, the "official pool" products will typically be 10% to 12% Sodium Hypochlorite.

    So yeah, we use ordinary bleach.
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

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