White residue on newly painted concrete pool

[oldnewbie]

We repainted our old in-ground pool (fiberglass sides and concrete bowl) with chlorinated rubber which we've used on all previous paintings. Paint had plenty of time to cure but before we could refill it, got a couple of feet of rain water at the bottom. After pumping that out it left a powdery white residue that will not brush off. This same residue was in the pool when we emptied it to repaint. We thought the surface looked white because the paint had worn away, but that residue came off with pressure washing. So I figured we had a chemistry problem last year that must have caused this stain. But now just rain water is causing the same thing to happen. Does anyone know what caused this? I've heard of this happening to old fiberglass, but this is just on the concrete part.

[PoolDoc]

What brand & type of paint did you use?

I've seen this with some acrylic paint, and also some low-cost epoxy. The acrylic was horrible (fortunately, I had not applied it, but had recommended against it), and had to be ground off.

[oldnewbie]

It was Olympic chlorinated rubber.

[PoolDoc]

That's high quality product, even if it is rubber.

Call Kelley, and ask them. I've never used their rubber based paint, so I don't know what 'failure modes' it has.

Kelley Technical Coatings.
1445 South 15th Street P.O. Box 3726
Louisville, Kentucky 40201-3726
502.636.2561 800.458.2842 Fax 502.635.5170

[oldnewbie]

Thanks for the advice. I called them and they say that since the white stuff will come off it can't have anything to do with the paint. He thinks it has to do with something in the water, possibly calcium. I know our area has very hard water - just confused that rain water would cause it.
Any other thoughts?

[PoolDoc]

Possibly, but I'm skeptical. Unfortunately the guru there that I used to call is retired.

Did you add calcium after filling the pool? How long ago did you paint?

Probably, you'll need to get a K2006 -- not as if you don't need one, anyhow -- and test the alkalinity and calcium levels on BOTH your pool, and the water you fill with. Even if that's not the problem, you are going to need valid test results before you can go back to Kelley and try to get more info. Test kit page link is in my blue signature box below.