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Thread: Black Algae ... HELP!!

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    Black Algae ... HELP!!

    Hi All,

    I have a black algae problem. Its not bad ... yet. It was recommended to me that I use Black Treat (by United), and TriChlor. This is a saltwater pool. Is this bad advice? I am driving myself crazy with this!!

    Here are my numbers

    FAC = 2
    TAC = 2
    PH = 8
    TA = 80
    CYA = 15
    Hardness = 70
    Phosphates = 1000

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    Mod Squad jblizzle's Avatar
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    Re: Black Algae ... HELP!!

    For a SWG pool your CYA is way low. So the trichlor could help to add some of the CYA you need, but I would think using liquid chlorine would allow you to raise the FC levels quicker to attack the algae.

    Is it localized? Are they thinking you should rub the Puck directly on the algae? I do not think ant special chemical would be needed beyond chlorine.

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    Isaac-1's Avatar
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    Re: Black Algae ... HELP!!

    In general we recomend that you stay away from all algaecides, chlorine alone should kill any algae as long as your CYA levels are not sky high, yours are on the Low side, and you will want to adjust that at some point soon, probably easiest by just using powdered CYA stabilizer once you get the algae problem solved.

    For your general information: Tri-chlor will raise both chlorine levels and CYA, however it does disolve slowly, dichlor powder (often sold as "shock", but not all "shocks" are dichlor) will also add both chlorine and CYA and disolves faster.

    As to what to do now, you will want to raise your pool water to "shock" (process not product) level and keep it there until the algae is dead, your CC is 0 and you don't loose any FC (chlorine) overnight. Shock level will depend on your CYA level (see the pool school link in the upper right corner of any page here), therefore using bleach/liquid chlorine to reach and maintain shock level would be easier than using dichlor to shock since with dichlor you would be trying to maintain a moving target level as your shock level would be changing as you go.

    Ike
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    Re: Black Algae ... HELP!!

    Is your pool vinyl or masonry? can you post a pic of the black algae?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Black Algae ... HELP!!

    Quote Originally Posted by duraleigh
    Is your pool vinyl or masonry? can you post a pic of the black algae?
    Its a masonry pool with diamond brite.
    Pics attached
    Attached Images Attached Images

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    Re: Black Algae ... HELP!!

    Looks like black algae to me, too. What is the tan square?

    Black algae is tough because of it's nature to grow "roots" into the masonry surface and form a protective film over itself.

    To get rid of it, you must elevate your levels of chlorine and then HOLD THEM ELEVATED until the Black Algae has disappeared. Next you must brush the algae vigorously often with a stainless steel brush to remove that protective film and expose thealgae to the elevated chlorine levels. Once daily is not too often to brush and it should be continued until NO trace of the algae remains.

    Prevention is to maintain proper chlorine levels and recheck the spots where it once occurred brushing and removing any spots that may reappear. It is also not a bad idea to elevate your chlorine levels permanently about 50% above what is suggested to aid in prevention.

    Yes, your CYA is w-a-a-y to low for an SWG pool....should be 60-70ppm.
    Dave S.
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    Butterfly's Avatar
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    Re: Black Algae ... HELP!!

    Quote Originally Posted by redneck6497
    Hi All,

    I have a black algae problem. Its not bad ... yet. It was recommended to me that I use Black Treat (by United), and TriChlor. This is a saltwater pool. Is this bad advice? I am driving myself crazy with this!!

    Here are my numbers

    FAC = 2
    TAC = 2
    PH = 8
    TA = 80
    CYA = 15
    Hardness = 70
    Phosphates = 1000
    You have gotten excellent advice!

    Suggested steps:

    1. Lower pH to about 7.4

    2. Add CYA via sock method to reach about 30PPM (but have enough on hand to increase to 70ish after you are done shocking.)

    3. Start the shock process as described in Pool School.

    4. You will need to use a stainless steel/algae brush to knock off the heads of the black algae to allow the chlorine in for the kill. Be careful with the s/s brush around that piece of tile (tan square?). You may need to get a tiny s/s brush for the sides around that.

    5. If you are able to rub a trichlor tab directly on the black algae, that will help.

    6. Leave the SWG off during the shocking.

    It would be helpful if you added your pool and equipment specs in your sig. Go to User Control Panel (upper left under TFP logo), select Profile, then Edit Sig.

    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 ... HELP!!

    Quote Originally Posted by Butterfly
    Quote Originally Posted by redneck6497
    Hi All,


    Phosphates = 1000
    You have gotten excellent advice!

    Suggested steps:

    1. Lower pH to about 7.4

    2. Add CYA via sock method to reach about 30PPM (but have enough on hand to increase to 70ish after you are done shocking.)

    3. Start the shock process as described in Pool School.

    4. You will need to use a stainless steel/algae brush to knock off the heads of the black algae to allow the chlorine in for the kill. Be careful with the s/s brush around that piece of tile (tan square?). You may need to get a tiny s/s brush for the sides around that.

    5. If you are able to rub a trichlor tab directly on the black algae, that will help.

    6. Leave the SWG off during the shocking.

    It would be helpful if you added your pool and equipment specs in your sig. Go to User Control Panel (upper left under TFP logo), select Profile, then Edit Sig.

    Welcome to the forum
    First, let me say thanks for all of the great comments, and help!!
    Okay, So I won't use the algaecide (from what I gather from the above emails). I will lower the PH. From what I gathered about the sock method for increasing CYA, I will add 48oz by volume of granulated stabilizer. I will split this in 2 athletic socks, and put one in each skimmer basket. I assume I will need to wait for everything to be dissolved. This will get me up to 30ppm according to the pool calculator. One question here is that this could take a while ... so am I hurting myself by not having elevated levels of chlorine? We have had tons of rain lately too.

    One thing I'm not sure about it how to dose the tricolor (I have this in granulated form). Where do I put it? Is there a chart somewhere? Do I put the entire does in at one time?

    And, I've already screwed up. I put in too much acid and reduced my Ph to 6.8 I guess I need to get some baking soda and get it back up again? I tested it about an hr. after adding the acid, maybe it just hasn't incorporated well enough (since I took a sample from the top)?

    Sorry about all of these questions. I'm learning a lot though.

  9. Back To Top    #9
    Butterfly's Avatar
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    Re: Black Algae ... HELP!!

    Quote Originally Posted by redneck6497
    First, let me say thanks for all of the great comments, and help!!
    Okay, So I won't use the algaecide (from what I gather from the above emails). I will lower the PH. From what I gathered about the sock method for increasing CYA, I will add 48oz by volume of granulated stabilizer. I will split this in 2 athletic socks, and put one in each skimmer basket. I assume I will need to wait for everything to be dissolved. This will get me up to 30ppm according to the pool calculator. One question here is that this could take a while ... so am I hurting myself by not having elevated levels of chlorine? We have had tons of rain lately too.
    Hang the socks of CYA and start shocking to shock value of 10 FC.

    One thing I'm not sure about it how to dose the tricolor (I have this in granulated form). Where do I put it? Is there a chart somewhere? Do I put the entire does in at one time?
    Did you read Pool School re: How to Shock Your Pool? We recommend bleach/liquid chlorine. You can find dose calcs at the PoolCalculator.com. Link in my sig. Give it a try and if you have questions, post back.

    And, I've already screwed up. I put in too much acid and reduced my Ph to 6.8 I guess I need to get some baking soda and get it back up again? I tested it about an hr. after adding the acid, maybe it just hasn't incorporated well enough (since I took a sample from the top)?
    The pH needs to be around 7.4ish. Retest BEFORE you dose. Also, baking soda is used to raise TA, NOT pH. We use borax to raise pH.

    Sorry about all of these questions. I'm learning a lot though.
    No problem, that is why we are here! Got lots of folks around to help out, 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!

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    Isaac-1's Avatar
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    Re: Black Algae ... HELP!!

    Don't use CYA Stabilizer AND trichlor, Trichlor (and dichlor) will add both chlorine and CYA this will result in your CYA level getting too high. For shocking it is a lot simpler if you use liquid chlorine / bleach and you do want to go ahead and get the shock process started while you wait for the CYA to disolve.
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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    ~Remember TFP counts on your donations to keep this site ad free~

  11. Back To Top    #11
    Butterfly's Avatar
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    Re: Black Algae ... HELP!!

    Just to reiterate, getting the pH to about 7.4 is the first order of business.
    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!

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