Plaster Stains

[rocks]

How do I go about getting rid of plaster stains?

I purchased a foreclosed home with a pool. This is my first pool and for the most part everything has gone well.

The pool obviously was not taken care of for some time prior to me buying the house. The back yard is surrounded by a lot of trees and I think that falling leaves are what stained the pool. Goodness knows there was a ton of muck when I cleaned it out the first time.

Do I have to replaster? the plaster looks good, no cracks, just stains.

How to go about removing the stains?

I cant get an image attached for some reason, dont have the time to figure it out right now.

[Pool Clown]

If the stains are from organics, they just might resolve themselves with a good shocking (High Chlorine levels).

[rocks]

They are pretty persistent.

After 2 seasons they have not altered much, even after major shocking.

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[rocks]

Anybody?

[Telemundo]

Anybody?

Large areas of plant and algae stains can be removed by draining and acid washing the entire pool. however, for smaller stains, cut a length of 1 1/2 inch pvc pipe long enough to reach the stain on the floor, and stick out of the water about 2 feet. get some muriatic acid, and position the pipe as vertical as possible onto the stained area. pour the acid into the pipe CAREFULLY! the acid can burn your hands, (should wear goggles too) the acid is heavier thatn the water and will sink into the bottom with minimal weakening. (a lot of water makes the acid too weak to be effective) when you see the acid start to come out the bottom of the pipe, (an oily looking yellowish cloud) wait a minute and then remove the pipe. this simply directs the acid onto the stain directly, and avoids the need to drain the pool. it may take a few shots of acid to do the trick. its a good idea to use your brush and brush the acid around after the stain is gone. you also may have to adjust ph the next day, since the acid will lower the PH.

[chem geek]

If it's black algae, then it should get reduced by brushing and high chlorine including rubbing a Trichlor puck on it (organic stains will also fade this way). If the stains are metal (especially iron), then put a Vitamin C tablet on top of it and it should fade. If this works, then you can use ascorbic acid to treat the entire pool as described in Metals in the Water and Metal Stains.

[rocks]

Thanks for the replies, good ideas.

I may just drain next spring and acid wash the whole pool.

[waterbear]

Test the stains so you know what will remove them,

first, hold a trichlor tab on a stained area for about 15 minutes. (use your pole or devise some way to keep it on the stain. Don't hold it in your hand!) If the stain lifts or disappears then a very high shock level can bleach the stain as can sodium percarbonate since it is organic

If not get some plain vitamin C tablets at the drugstore and put them in an old white sock. Hold this on the stained area. If the stain lifts in a minute or two it is metal and can be removed with an ascorbic, citric, or oxalic acid treatment (these are organic reducing acids that can remove metal stains from pools when added to the water).

If that does not work put some dry acid (sodium bisulfate) in another old sock and hold it on the stain about 30 minutes. If that works you will need to drain and acid wash.

Try these tests and let us know. We can then help you with the proper procedure. If either of the first ones are successful you do not have t drain and acid wash. Each time you acid wash you remove a bit of plaster and shorten the life of your finish so you want to do it only as a last resort.