Dissolving pool coping

[Marts99ss]

[FONT=&quot]Hello people does anyone know what's going on with my pool coping. It's like acid is being socked up and it's dissolving the concrete coping. Have you ever seen anything like this? What's going on? How do can I stop it?

Thank you all,
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[toofast]

So can you give us a few more details like age and how you add and who adds chemicals and if it's a salt or fresh water chlorinated pool

 

[JodieM]

Salt will eat at your concrete. Be sure when you put it in that you don't let any sit on the concrete, brush it away.

 

[Rocco]

Do you put any powdered shock or PH down in the pool? I have seen powdered shock leave small holes in flag stone before.

 

[Marts99ss]

Thanks guys, I put in my own chemicals. When I put salt in it's always at the deep end and brush it off. The stains are at the edges of the coping. And then after a while it eats away the concrete. All of them are around the shallow end. A couple of times in the past I've put acid around the whole pool in the shallow and also with that do any harm? In general I have to add acid every week to my pool because I have raised spa I get a lot of air ration so my pH goes up. I keep my alkalinity around 110. and pH 7.2 - 7.8.

 

[JamesW]

Since the effect is mostly along a grout line, I suspect that it's probably efflorescence.

Is most of the effect along grout lines?

Do you get a really wet ground at times?

 

[Marts99ss]

Yes, You are absolutely right it's all along the edges of the grout and it's on the side that gets wet a lot and stays wet a lot. And I also see this I think coming out of the concrete decking. But how does this eat away the concrete cement? How do I stop it? Is there a test to make sure it's really that?

 

[JamesW]

I’m pretty sure that at least some of what you’re seeing is due to efflorescence. Water can saturate the concrete, grout etc and dissolve some of the minerals. They migrate to the surface and are deposited as the water dries.

I would suggest that you try to control the water such that the area is not constantly wet.

 

[pushin glass]

I agree it's probably efflorescence and seems to be coming from your mortar joints. If you clean it off (can use a stiff bristled brush and water or surekleen and an acid brush), seal your coping and mortar joints with a silane/siloxane sealant and the problem might not return. Seal your deck while you are at it. The degradation may be due to salt damage as the water evaporates, but also if water is in the concrete and heats up, it will expand and can damage it as well.