Can you remove iron stains in an empty pool

markayash

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Its snowing in Georgia so maybe bored :)
I have some stains that are iron although I don't think I have iron in my county water so not sure why they keep coming back.

They did do a lot of water line work around the time I filled it years ago and my whole house water filter ( I by pass it when filling ) turned dark brown. That was the first and last time that has happened.

But my thought is draining the pool in early spring and washing it and filling fresh. If I added Ascorbic acid and drained it the next day would that remove the iron? Or would moxing a strong ascorbic solution and spraying the walls work better.

I am on a hill so no concerns draining and refilling, In fact I drain it about a foot down over the winter
 

JohnT

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I’d say draining would get rid of the iron best. Using ascorbic acid converts the iron to a different form that is water soluble. I don’t know what the effect of surface application would be. I’d be concerned with streaking.

Fully draining a pool is not a simple thing. If you have much groundwater, the pressure lifting the pool can be extreme.
 
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JoyfulNoise

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Yes, you can wash concrete surfaces with an iron stain remover. I would not use AA though. You can go to any masonry supply store and ask them for a concrete cleaner that specializes in iron/rust stains. You’d scrub it in with a stiff Tampico masonry brush and then have someone power wash behind you. The rinse water can be picked up in the deep end with a submersible pump and discharged out. If it’s acidic, you can keep some baking soda on hand and just a throw a few pounds of it into the water that pools around the sub pump.
 
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JoyfulNoise

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You’re in GA though so you have to be very careful about ground water and make sure your hydrostatic valve is open or else you can accidentally float your pool.
 
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markayash

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Yes, you can wash concrete surfaces with an iron stain remover. I would not use AA though. You can go to any masonry supply store and ask them for a concrete cleaner that specializes in iron/rust stains. You’d scrub it in with a stiff Tampico masonry brush and then have someone power wash behind you. The rinse water can be picked up in the deep end with a submersible pump and discharged out. If it’s acidic, you can keep some baking soda on hand and just a throw a few pounds of it into the water that pools around the sub pump.
Was just reading the article about treating iron stains. Since I would be spraying an empty pool what about oxalic acid? Article said you have to be careful in high CH pools but mine would be on bare plaster. I can do either one, just curious which would work best. I still have a couple months before I drain it
 

JoyfulNoise

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AA is better than oxalic acid because residual OA can react with chlorine and form unhealthy chlorinated organics. Both will have low pH so you need to be careful spraying it if there’s any natural stone around as it ca leach metals out of the stone. I suggest you carefully consider your plans for this and make sure that you mask off area that you don’t want the acidic overspray hitting. Also, if you have iron laden water in the pool right now, chances are the plaster probably has iron stains uniformly over all the surface and so if you hit just one area with AA, the plaster could significantly change color which will then go from having one small iron stain to one big color change. So be prepared to spray and brush the entire pool surface to ensure a uniform change in color.

Which then begs the question - why are you bothering to do it this way? When the time comes, simply add AA to the old water and let it react uniformly with the entire pool surface and then drain the pool. That way you’ll ensure a uniform change in color. Walking around the bottom of an empty plaster pool spraying chemicals and scrubbing walls is no fun, believe me.
 

markayash

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Mar 21, 2016
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AA is better than oxalic acid because residual OA can react with chlorine and form unhealthy chlorinated organics. Both will have low pH so you need to be careful spraying it if there’s any natural stone around as it ca leach metals out of the stone. I suggest you carefully consider your plans for this and make sure that you mask off area that you don’t want the acidic overspray hitting. Also, if you have iron laden water in the pool right now, chances are the plaster probably has iron stains uniformly over all the surface and so if you hit just one area with AA, the plaster could significantly change color which will then go from having one small iron stain to one big color change. So be prepared to spray and brush the entire pool surface to ensure a uniform change in color.

Which then begs the question - why are you bothering to do it this way? When the time comes, simply add AA to the old water and let it react uniformly with the entire pool surface and then drain the pool. That way you’ll ensure a uniform change in color. Walking around the bottom of an empty plaster pool spraying chemicals and scrubbing walls is no fun, believe me.
I debated That also, any chemical harm leaving the pool with a healthy dose of AA for a coupe of days? It will be still cold so not worried about algae as much
 

JoyfulNoise

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I debated That also, any chemical harm leaving the pool with a healthy dose of AA for a coupe of days? It will be still cold so not worried about algae as much

As long as there is no heater exposed or the heater is bypassed it should be fine. If I were doing it that way I would bypass all the equipment (turn it all off and drain it) and then just use the submersible pump to mix the water while dissolving in the AA. Since you need the sub pump anyway to drain the pool, might as well use it.
 
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