Mustard stains but not algae, what is it?!

Stains on the pool surfaces, pool equipment
or on the swimmers, or off-color swimming pool
water. Discolored but clear pool water.
corsara
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My Pool: 36 x 18, vinyl liner
Location: Ontario, Canada

Mustard stains but not algae, what is it?!

Postby corsara » Sat 29 May, 2010 00:31

Thanks. I will try that then.

Any idea where I can buy the ascorbic acid, I don't think they had in the pool shop?! Same as sequestrant? I this something that is exclusively pool-related or it is of more generic nature that I can find in other kind of stores?

Thanks!


corsara
Pool Enthusiast
Pool Enthusiast
Posts: 20
Joined: Tue 04 May, 2010 10:42
My Pool: 36 x 18, vinyl liner
Location: Ontario, Canada

Mustard stains but not algae, what is it?!

Postby corsara » Sat 29 May, 2010 00:38

So, I mentioned that I bought some stuff, this is the stuff: http://discounterspoolandspa.com/store/ ... 76C68.aspx

I poured 1 litre of this thing in my pool (about 95k litres). However, my Chlorine level is about 5 ppm right now, so I wonder if I had wasted the product.. do you think this might be a possible alternative to the treatment with ascorbic acid? In all cases, I will report the results here tomorrow!
chem geek
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Mustard stains but not algae, what is it?!

Postby chem geek » Sat 29 May, 2010 02:13

That is mostly a metal sequestrant that you will need anyway, but it doesn't remove the stains as well as ascorbic acid. The link I gave in the earlier post on Metals in the Water and Metal Stains gives this link to instructions including sources of ascorbic acid. You can also use citric acid or oxalic acid which are less expensive, but it takes more and they may take longer.
kiwiswimmer

Mustard stains but not algae, what is it?!

Postby kiwiswimmer » Sun 30 May, 2010 11:17

Hi. I find your posts interesting as I have BOTH mustard algae and exactly the same staining on about 40% of my pool liner floor. It feels like sandpaper to touch and does not scrub off. The guy at the pool store thinks it may be a fungus permeated from under the liner. I plan on trying to get rid of the mustard algae first and then attack the stain. I was also concered about my kids safety but it seems that as long as you keep chlorine levels and others at a "normal" rate it should be OK until fixed. Good luck!
Regina

Mustard stains but not algae, what is it?!

Postby Regina » Wed 09 Jun, 2010 20:49

I'm having the same problem. My jets and steps have a yellow mustard color stain that can't be brushed nor scrubed off (even tried dry earser no results) While the chlorine was low I used stain out to move the stain which worked but as soon as the chlorine level raised to the normal the stain comes back. Tested the water which is not showing any cooper nor iron. All levels test normal but no explaination of why everything is staining. I've not had any luck at two different pool stores to get any help with to resolve the problem. My water is clear and very sparkle.
chem geek
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Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Mustard stains but not algae, what is it?!

Postby chem geek » Thu 10 Jun, 2010 14:53

Try the ascorbic acid (vitamin C) test and if the stain fades then do that treatment described in the link I gave earlier. You likely have an iron stain in spite of their not being any such measurement in the water -- all of the iron is in the stain and may have precipitated out completely so as not to measure any metal ions left in the water.
Sunburst

Mustard stains but not algae, what is it?!

Postby Sunburst » Mon 21 Jun, 2010 10:29

We're having the EXACT same issue with our vinyl iner inground pool. Large brownish stains over half of the pool floor. The stains however definitely feel slimy, but you can not brush away the stain no matter how hard you try.

I'm going to try the vitamin C trick tonight to see if this has any effect. Please let me know if you find a solution.
summerlover
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Joined: Sat 17 Jul, 2010 09:08
My Pool: 16x32 in-ground, vinyl liner, chlorine
Location: Omaha Nebraska

Mustard stains but not algae, what is it?!

Postby summerlover » Wed 21 Jul, 2010 21:24

we have the same thing and have done the acsorbic acid twice at $48 a time and it lasts less than a week. Our water tested negative for iron, 1st time pH and alkalinity were low and the pool store told me to use 17 pounds of soda ash, after adding only 10 pounds it shot my levels way up and made the water cloudy. Now after the 2nd time I have no chlorine and my phosphates went from 100 to 500. The water is crystal clear but with the staining looks like [email protected], I am also at a loss and the people at the pool store don't know what to tell you. Do I try phos free or algicide? Initially I was told I wouldn't need to keep doing the stain free more than once. I have scrubbed the pool and nothing helps
chem geek
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Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Mustard stains but not algae, what is it?!

Postby chem geek » Wed 21 Jul, 2010 21:27

The ascorbic acid treatment only removes the stain, but you need a metal sequestrant to keep the metal in solution and that needs to be added regularly. The better metal sequestrants use HEDP and don't break down quickly by chlorine. Read Metals in the Water and Metal Stains for more info. If you don't use enough metal sequestrant (or use a poor one) or you raise the chlorine or pH levels up too high or too quickly, then the stains can return.

There are other techniques to forcibly precipitate metals so they can be filtered out with a good filter or with batting material, but these techniques (which mostly involve raising the pH) can deposit stains back onto pool surfaces. This works OK for vinyl where the staining is less likely, but is not a great technique for plaster pools or fiberglass that stains more readily.

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