Brown Stain after a AA battery was found in pool

[jjgleeson]

Hello can anyone help
I found a AA battery in my new pool, I have no idea who threw it in but it must have been in my salt water pool for about 3 or 4 days. I had rusted slightly and left a dark drown spot on the bottom of my new pool. The pool is salt water and about a year old. Its got pepple tec coating and I tried a standard brush but it does not take the stain away. Is there a simple solution besides draining the pool to get rid of this type of stain. I imagine its rust and its the size of a small fist.
Please help if you know something I can try.
Thank you
James

[TSH Tech]

Salt pool AND Pebble Tec? Oh man, you had to make this difficult.

Ok, here's what you do first, make sure your water chemistry is all dialed in correctly before anything, Chlorine, Ph, Alkalinity... Once you get that squared away, then we can move on.

Pebble Tec unlike plaster, is rocks and resin, so stain removal is going to work a little differently than traditional methods on plaster. What I'm going to say next might come as a surprise to you, but this is a least abrasive method that won't ruin your Pebble Tec. Go to the health/vitamin store and buy a bottle of Vitamin C tablets. Not capsules, dry tablets. Don't go cheap on the tablets, but at the same time, don't get the super expensive ones, what you're looking for is Ascorbic Acid content in the Vitamin C. Your going to take a small handful of those tablets and place them on the stain. You may have to push them into position with a pool brush or something useful. Take out your pool sweep if you have one and keep the system off overnight to keep the water calm, while the tablets slowly dissolve and work on the stain. Keep applying the tablets until the stain looks like it is gone. Keep in mind, this is not going to be an instant stain removal method, it may take a week or probably a month, it may vary.

Why this method?
Rust stains need to release from the surface in which it has bonded. The natural acid contained within vitamin C is enough to help break the rust structure away from the surface, yet not strong enough to put a hole in your Pebble Tec damaging your finish. Try this method first.

[chem geek]

Ascorbic acid is also a reducing agent so it reduces the ferric iron to ferrous iron that is more soluble in the water. However, if you've got chlorine in the water, then it will re-oxidize the ferrous back to ferric and potentially cause stains elsewhere unless you have a metal sequestrant in the water. The usual procedure (at least for plaster) is described in Metals in the Water and Metal Stains.

[Jeff1109]

I have the same issue. However I have plaster and the plaster is almost 3 weeks old. We have not put the salt in the water yet (salt water pool). Can you provide a solution for this senario? Thanks in advance.