Stain Removal-Acid Wash Questions???

mmcwhorter

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Jul 13, 2015
382
Huntingtown, MD
SO, I guess this is the right forum for THIS topic...as none of the others jumped out at me... :)

On another thread I mentioned we are soon to be draining the pool for a tile restore job in about three weeks. My plaster looks pretty good...and it is a lot smoother than my last pool...but the tiles are a mess. Falling off 2-3 per week and completely covered by spa overflow wall with thick white caked on rock hard material... (calcium I presume). I guess the prior home-owner of this pool didn't close the pool properly and didn't keep the pool balanced....both and/or whatever....This has been pretty much verified by my new neighbors. LOL.

i am wondering if this is a good opportunity to remove some pool wall/floor stains.

As to the stains:
95% of the pool surface looks great from the deck. There are about 5-6 places on pool walls and floor that have yellow-brownish stains. On the floor they are circular and irregular...at both deep and shallow ends...on the walls they typically look like yellow drips down the wall, wider at the water-line and narrower toward the bottom. On the walls they kind of look like an inverted stalagmite.

These satins are permanent. They will not brush away.

These are also identical stains that I had in my spa one year ago when I moved in to this house. I was able to remove them completely with a simple spray bottle mix of 50-50 Muriatic Acid 31.25 / water. I drained the spa completely (easy to do that!!!), sprayed the yellow spots with a fine mist of the 50-50 blend.......the yellow spots bubbled up like butter in a frying pan....I quickly rinsed the stain and it was gone. i also put a few cups of Borax in the bottom of the spa to neutralize any acid until I could get the water flowing back in from the pump....I was concerned about the acid pooling at the bottom of the spa during the stain removal...The spa, when refilled, looked 1000 times better.

So, I am thinking about doing the same with the pool while it is drained during the tile renovation project. I was considering doing it after the first day when the old tile demolish job has been completed...and they have cleaned to pool out for the next day's effort...which is to start the installation of the new tile/coping.

Are there any pitfalls or concerns I need to be aware of? Any better ways to do this other than muriatic acid, etc???? Is it safe to walk in an empty pool with static plugs pulled? i don't think I am near a low water table, in fact my pool location in the back yard is on a hill 8 feet above the roadway in the front. My old pool was FL with very low water tables and that was always a concern.

Thanks in advance. Again, great website.
 
The way you dealt with the spa stains is exactly right. Muriatic acid is the best for stain removal yes, its okay to walk inside the pool but be careful not to leave footprints. Also, do not let any acid roll down the pool walls that will cause streaking. Liberal use of a hose and a submersible pump is a necessary tool. If possible, a constant neutralizing of the acid is a good idea. As for draining your pool, I don't know your area well enough but I assume that your repair company would be responsible for the draining of your pool.
 
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