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Thread: Black algae... I HATE black algae!

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    Black algae... I HATE black algae!

    Ok folks, after a winter of little or no maintenance my black algea seems like it is winning the battle! I have a plaster pool that needs refinishing and I unfortunately do not have the funds required to do the refinish. I have been fighting a war against this black algae for a few years now...

    In the past, the battle was mainly on the walls. I have won a few battles by sprinkling trichlor right on the walls with the equipment off. (So that the powder would get attached to the algae) I think I purchased a 50 lbs bucket of trichlor pucks and crushed them down, putting the whole bucketfull inthe pool. (Overkill perhaps but the battle was won! Now it seems to have also spread to the bottom.

    SO, the first thing that I am trying to obtain trichlor powder in bulk. Anyone know where I could find that?

    Secondly, I am open to any and all suggestions.

    Thank you very much!

    The pool is 20' X 40', 6' deep in the middle and perhaps 4' on each end (V shape bottom), I therefore estimate it to contain 25 000 gallons.

    The PH is presently low.

    I have a sand filter.

    I was wondering if I should try to brush it with a S-S brush or better to leave it there and nuke it with trichlor, and then brush it?

    Should I run the pump continuously or leave it off after I nuke it and/or brush it?

    PLEASE HELP!!!

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    Re: Black algae... I HATE black algae!

    My first inclination is to believe your CYA is w-a-a-ay too high.

    Can you post test results so we can help you get started?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Black algae... I HATE black algae!

    Quote Originally Posted by duraleigh
    My first inclination is to believe your CYA is w-a-a-ay too high.

    Can you post test results so we can help you get started?
    All I can test myself now are the basic stuff of PH and Chlorine levels.

    PH is about 7.2
    Chlorine looke like between 2 and 4 (ppm?) (In the middle of the chart on the tester...)

    I will be able to get it more thoroughly tested at the pool store on Tuesday.

    Thanks.

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    Re: Black algae... I HATE black algae!

    Until you can test the CYA, it is just guesswork to suggest how to proceed.

    pH is just fine @ 7.2

    Make sure the pool store tests for CYA, CH, and TA. Might as well have them retest your pH and FC, too.

    Again, I suspect you are going to have to shock the pool but you may very well need to do a partial drain first to get your CYA down to something manageable. Again, I emphasize, it's all just a guess until you can post some reliable test results.

    Pool School has a lot of great information. I suggest you start reading ABC's of Pool Water Chemistry.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Black algae... I HATE black algae!

    Quote Originally Posted by duraleigh
    Until you can test the CYA, it is just guesswork to suggest how to proceed.

    pH is just fine @ 7.2

    Make sure the pool store tests for CYA, CH, and TA. Might as well have them retest your pH and FC, too.

    Again, I suspect you are going to have to shock the pool but you may very well need to do a partial drain first to get your CYA down to something manageable. Again, I emphasize, it's all just a guess until you can post some reliable test results.

    Pool School has a lot of great information. I suggest you start reading ABC's of Pool Water Chemistry.
    I have been having this battle for 3 years now. I kinda sorta know a thing or two about pools and pool chemistry, trust me that my main issue is that I have cracks in my plaster and I have bblack algae which has setup shop with it's tremendous roots.

    As mentioned, I have previously won the battle with trichlor. The main issue this winter is that I was away and my helper did not stay on top of things and there was no chlorine in the pool for at least 5 months which enabled the algae to propagate and thrive.

    I will have the water as thoroughly tested as I can on Tuesday, post that along with pics on Tuesday.

    Do you know where I can buy bulk powder chlorine shock?

    Thanks.

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    Butterfly's Avatar
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    Re: Black algae... I HATE black algae!

    Well, I agree with duraleigh that your pool is most likely overstabilized and adding trichlor will only compound the problem.

    You really need a good test kit like the TF100 or Taylor K-2006 to put you in control of your pool. You can read about the test kit comparisons in Pool School.

    TFP, a good test kit, Pool School and the PoolCalculator.com are your new best friends.

    When you post some test #'s, we can start helping.

    Welcome to the forum
    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: Black algae... I HATE black algae!

    Well, I would perhaps think of it a little differently. You have algae because your chlorine is/has been inadequate. There is a good chance it has been inadequate because your CYA is so high it has rendered your chlorine ineffective.

    Tri-chlor tabs and powdered "shock" all contain CYA and it NEVER leaves your pool....rendering your chlorine less and less effective as it accumulates.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Mod Squad Bama Rambler's Avatar
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    Re: Black algae... I HATE black algae!

    I think a good long read through Pool School would enlighten you a lot. It'll help you understand just how important keeping your CYA in check is in preventing all types of algae.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Black algae... I HATE black algae!

    Thanks all, I will:

    - Get the water tested at the local pool store.
    - Post the results.
    - Buy a better test kit which you have recommended
    - Wage a WAR and hopefully win!

    I do know that the ultimate solution is to empty the pool and get it refinished as it has many cracks and flaking due to the previous owners of the house (the bank) thinking that it was best to empty the pool instead of leaving it full of water. I have eggshell cracking all over the place as well as deeper cracks and flaking.

    Thanks again for welcoming me to the forum and not chastizing me!

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    Butterfly's Avatar
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    Re: Black algae... I HATE black algae!

    You have a good attitude and we are here to help.

    Now would be a good time for you to add your pool and equipment specs to your signature.
    Go to User Control Panel (upper left under TFP logo), select Profile, then edit Sig.

    Also add your location (city and state) in your profile because that helps us with answering questions.

    We'd also love to see a pic of your pool!

    btw, we all HATE black algae, too!
    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.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  11. Back To Top    #11

    Re: Black algae... I HATE black algae!

    I have been in different forums (not about pools) where people are curt and not very nice! (Not the case here...)

    I will double check my equipment, but I believe I have a 2hp Hayward pump and a medium size sand filter! DUH!

    As soon as I confirm it, I will put it in my signature.

    The pool is located in Cottonwood, AZ. It also has a bubble pool cover, should that be on or ff the pool? The issue now is that the pool is surrounded by big mulberry trees which are spreading their pollen these days, so we have ellected to leave the cover on the pool...

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    Butterfly's Avatar
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    Re: Black algae... I HATE black algae!

    Quote Originally Posted by DesertRoseBnB
    I have been in different forums (not about pools) where people are curt and not very nice! (Not the case here...)
    We thank you for the compliment

    I will double check my equipment, but I believe I have a 2hp Hayward pump and a medium size sand filter! DUH!

    As soon as I confirm it, I will put it in my signature.

    The pool is located in Cottonwood, AZ. It also has a bubble pool cover, should that be on or ff the pool? The issue now is that the pool is surrounded by big mulberry trees which are spreading their pollen these days, so we have ellected to leave the cover on the pool...
    Do what you want for now, but when you start shocking the cover needs to come off
    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.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  13. Back To Top    #13

    Re: Black algae... I HATE black algae!

    Sorry for the delay folks, just got the CNA tested at the local pool store and the reading is 0.0!!!

    So, how do you guys suggest we proceed?

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    Re: Black algae... I HATE black algae!

    Here are all the test numbers:

    0.0 CYA
    400 CAL
    100 ALC
    7.2 PH
    .5 CHLOR

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    Re: Black algae... I HATE black algae!

    99% positive that your CYA result is not even close. Time to go to another pool store until you get your test kit. Before I started testing myself, my pool store told me last season that my CYA was 0. I proceeded to add, tested myself when it arrived, and found that I was 100+.

    Reason I say that it's not even close is that you put 50 lbs of pulverized pucks in. I'm assuming you're CYA is actually sky-high.

    Try another store.....pool stores use diagnostic equipment, and like all diagnostic equipment, must be calibrated. Never know how often that happens!

    You've got algae because you have no chlorine. Once you get your CYA back to a manageable level, you can begin the shock process based on the pool calculator, and should be eliminated.
    Kansas City, MO
    13500 gallon Foxx vinyl sport pool--inground (1988)
    Cristal-Flo sand filter
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    Re: Black algae... I HATE black algae!

    I wouldn't bother putting in any chemicals until you get your own test kit! I suspect you will be doing at least a partial drain to get your CYA in check.
    40'x19' IG Diamond Brite 29K 4' Waterfall/Dive Rock FNS60 DE Inteliflo VS 2hp Whisperflo pumps Aqualogic(P4) SWG TF100 Tester


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  17. Back To Top    #17

    Re: Black algae... I HATE black algae!

    I put in 50lbs of pulverised pucks about 1 year and a half ago which promptly cleared up the black algae. It has since returned because the pool was neglected during the winter months when there was very little if any chlorine.

    I will get the CNA re-tested and get back with another set of numbers...

    How much CNA is a "healthy" number?

  18. Back To Top    #18
    maxepr1's Avatar
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    Re: Black algae... I HATE black algae!

    CYA. 50 is a good starting point. I suggest you read Pool School(link in sig). Pool stores CONSTANTLY get wrong though! I would hold any test from a store with a grain of salt! Have you ordered a test kit and if so which one?
    40'x19' IG Diamond Brite 29K 4' Waterfall/Dive Rock FNS60 DE Inteliflo VS 2hp Whisperflo pumps Aqualogic(P4) SWG TF100 Tester


    Pool School, Pool Calculator,TFTestKits,

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    Mod Squad jblizzle's Avatar
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    Re: Black algae... I HATE black algae!

    Hey Neighbor ... well same state anyways

    You can find the Recommended Levels in Pool School. CYA of 30-50ppm is recommended if you do not have a SWG. Being sunny AZ ... closer to 50ppm is probably better.

    I again must suggest ordering a good test kit (see link in signature) and the TF100 really is the best value. While waiting for your kit, continue reading through Pool School and hopefully you will learn a little more about your pool chemistry ... I learn something new here every day.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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  20. Back To Top    #20
    linen's Avatar
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    Re: Black algae... I HATE black algae!

    Quote Originally Posted by DesertRoseBnB
    I put in 50lbs of pulverised pucks about 1 year and a half ago
    50 lbs of trichlor would have raised your 25000 gallon pools cya concentration to 133 ppm. It is unlikely at all of that disappeared, so it is likely that the pool store results are bunk. You need to get your own test kit (see my sig).
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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