Black Algae don't know what to do anymore ?

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
rdragona
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Black Algae don't know what to do anymore ?

Postby rdragona » Thu 07 May, 2009 00:42

Hello I have black algae in my pool and I don't know what to do. I don't have experience in pools. I am 15 and I'm cleaning pool as a chore. I had black algae a year ago but we called a pool guy and he dumped gallons of acids and conditioner then told us just keep conditioner between 20 and 30 and to vaccume the pool. This year it's back. I scrubbed the entire pool then used black algaecide which only made the water blue and a little bit of the algae go away. I have a salt water pool with the electric chlorine generator. The salt is at 2800pm, the conditioner is at 28, I run the pool from 10am-6pm, and I scrub it with a wire brush once a day. If any more info on pool chemistry is needed please ask and I could try to find out. What I need to know is what can I do to clean this? I don't think shock can be used cause I was told that was not for salt water pools. I will try to post a picture tomorrow around 4pm (i have school from 7am-3pm).


Me...
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Black Algae don't know what to do anymore ?

Postby Me... » Thu 07 May, 2009 08:09

Black Algae is the worst and will actually root in the pool wall. Might need an acid and/or chlorine wash to totally get rid of it. You will need to keep the water balanced and the chlorine at least 5ppm for while to see if it has any effect. Keep brushing and the pool and it should be running 24/7 when you have issues.
rdragona
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Black Algae don't know what to do anymore ?

Postby rdragona » Sun 10 May, 2009 16:16

I'm going to check the pool chemistry but I was wondering if the AquaChek® Silver 7-Way works with salt water pools.
Aquaclear-NZ
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Black Algae don't know what to do anymore ?

Postby Aquaclear-NZ » Mon 11 May, 2009 02:13

The Aquacheck 7 is a good quick test and is compatible with salt pools
best to take those readings and post the results

before shocking it is a good idea to lower pH to around 6.5 - 6.8, this helps open the waxy coating on the algae to help algaecide and chlorine to penetrate, making it easier to kill
Chocolate fish do not swim in hot water
rdragona
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Black Algae don't know what to do anymore ?

Postby rdragona » Tue 12 May, 2009 23:31

Alright I tested the water and this is what I got.

Total Hardness=300ppm
Total Chlorine and Total Bromine=0
Free Chlorine 0.5ppm
pH=8.4
Total Alkalinity=100ppm
Cyanuric Acid=130ppm
chem geek
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Black Algae don't know what to do anymore ?

Postby chem geek » Wed 13 May, 2009 01:19

This is very different than what you reported in your first post where the conditioner (CYA) was 28 ppm where now you are reporting 130 ppm. Your chlorine is low and your pH is high.

The high CYA makes more sense in terms of your getting black algae since it only grows slowly under conditions of too low an FC/CYA ratio over an extended period of time. You will need to shock the pool, but with the high CYA level it is better to do a partial drain/refill to lower the CYA first since you should shock with an FC level that is 40% of the CYA level (so obviously, 130 ppm CYA isn't very practical requiring 52 ppm FC).

I'm not sure I trust the test strip results. Some test strips are not very good. I always recommend either the Taylor K-2006 test kit which you can get at a good online price here or the TF100 from tftestkits.net here with the latter kit having 36% more volume of reagents so is less expensive per test.
rdragona
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Black Algae don't know what to do anymore ?

Postby rdragona » Wed 13 May, 2009 18:39

The first conditioner test is a liquid test with numbers from 20-100. The other is a strip test with 0-300

How do I lower cyanuric acid, lower pH, and raise free chlorine all at once?
Pooltech32
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Black Algae don't know what to do anymore ?

Postby Pooltech32 » Sat 16 May, 2009 23:33

you don't, I would drain half the pool first and as it is filling add some acid to lower the PH, your chlorine is more effective at the proper PH levels. Then I would add some chlorine to the pool. I never use test strips as they are not that accurate.

Once you have drained, filled, lowered the PH and added acid you should retest your CYA, if still high you may have to repeat until you get it to around 50-60ppm.

Black algea is one of the hardest to get rid of, you need to kill it directly with chlorine so that will mean either completly draining it and giving the pool a chlorine wash, or using an unstablized granular chlorine to kill the algea. But before you go dumping loads of granular chlorine in the pool I always do a test spot, try a corner in the shallow end and put a few tablespoons down the side and let it sit for a bit, (check your PH first, below 7.2 is not good for granular chlorine sometimes) if it turns black then you have copper in the water and the whole pool will turn black if you load it up. if not I would try broadcasting over the pool and letting it sit over night, then vacuum the pool to waste the following morning. By the way I would turn your SWG completly off and bypass it if you can.
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Black Algae don't know what to do anymore ?

Postby Guest » Tue 13 Aug, 2013 14:13

Pool User wrote:I

I have black spots which won't scrub off. I'm having a hard time keeping any FC in my pool. I shock and test and nothing! I've never had such a problem. The pool store thinks its black mold but isn't it uncommon to get in a vinyl pool? I have a 15x30 oval above ground vinyl pool. I tried scrubbing and using something called black mustard and then shocking. I'm confused?!?!?

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