Help.algae Or Cu Stain?

Stains on the pool surfaces, pool equipment
or on the swimmers, or off-color swimming pool
water. Discolored but clear pool water.
jasonfu
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Help.algae Or Cu Stain?

Postby jasonfu » Tue 13 Aug, 2013 13:18

So…I have a salt water pool 36” by 18” deep end is 9” deep. I had some “staining” on the bottom or the deep end, the pool store said my water was well balanced and that it is probably algae caused by the direction of the Jets. So I pointed the jets down directly at the Stain. This had no effect on the situation. So then they had me do a shock(3 of these little pouches) and a bottle of Erase. Stain went away…good right. Well 2 weeks later, pretty much over night, it came back worse, I have attached a picture. So I went to a different Pool store, told them the whole story, and they say it can only be one of two things, Copper staining or black Algae. They say they have never heard of black algae on a vinyl liner and that it is most likely copper staining, I should swim down and rub it with a vitamin C tablet??? So I tried that but 9” feet under water I only have so much scrubbing time, didn’t really come off. Anyone have any idea how to confirm what it is, seems to me like it is just a guessing game for the pool store at this point? They seem happy to sell me all kinds of chemicals? The pool is about 10 years old but new to me…I have no idea what I am doing but am on a fast learning curve…any help would be welcome.
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jasonfu
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Joined: Thu 24 Jan, 2013 13:53
Location: Ottawa

Help.algae Or Cu Stain?

Postby jasonfu » Thu 15 Aug, 2013 12:22

Soooo as an update and to vent my frustrations. Vitamin C did nothing, chorine tablet did make it fade. So now the “Pool Experts” say that is has to be Black algae, which is in the sand under my liner and that I have to replace the liner and the sand below it….this sound right to anyone? Seems like I went for an oil change and instead they just replaced the motor? HELP Anyone know how I can identify this stain for sure? Rubbing it with Chorine don't see like an exact science.
chem geek
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Help.algae Or Cu Stain?

Postby chem geek » Thu 15 Aug, 2013 13:40

If Vitamin C (ascorbic acid) did not remove it but a Trichlor puck faded it, then it is more likely to be an organic stain (say from leaves). It doesn't look like black algae to me. Either way, higher chlorine levels should fade it. If it were black algae, you'd want to use a rough brush (stainless steel, if a plaster pool) to scrape off the head of the black algae to expose deeper layers to high chlorine levels.

However, your active chlorine level is probably too low, possibly because your Cyanuric Acid (CYA) is too high making the chlorine much less effective. Read the Pool School to learn more about how to maintain your pool.
jasonfu
Pool Newbie
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Posts: 4
Joined: Thu 24 Jan, 2013 13:53
Location: Ottawa

Help.algae Or Cu Stain?

Postby jasonfu » Thu 15 Aug, 2013 14:20

Clorine is at 8ppm...I don't have any leaves in the pool...but have an issue with Carpenter ants in the pool...could that cause it.

The pool isn't plaster...it is Vinyl.
chem geek
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Help.algae Or Cu Stain?

Postby chem geek » Sat 17 Aug, 2013 00:12

What's your Cyanuric Acid (CYA) level? I agree with the pool store that it's unlikely for you to have black algae on vinyl.

So when you shocked before and used a bottle of Erase which I presume to be a metal sequestrant, it went away, but then came back. Ascorbic acid doesn't do well against copper -- it's better for iron stains. Oxalic acid is sometimes used for copper stains but it's somewhat nasty stuff. Did you use the [url=http://www.bioguard.com/Our_Products/Cleaners/Erase®_Copper_Stain_Remover]BioGuard® Erase® Copper Stain Remover[/url] as opposed to the [url=http://www.bioguard.com/Our_Products/Cleaners/Erase®_Iron_Stain_Remover]BioGuard® Erase® Iron Stain Remover[/url]? The latter isn't for vinyl pools so given what you said it does sound like you used a copper stain remover.

So how did copper get into this pool? Perhaps a copper algaecide was used and overdosed. So maybe you need to lower the pH, add more of the copper stain remover (note that it wants a low chlorine level, NOT a shock level of chlorine), and slowly raise the pH but try and keep it at 7.5 or below. To physically remove the copper from the water will require either water replacement or you can try to use the CuLator Metal Eliminator though that is expensive.

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