marble spillway is rough like sandpaper

[lborne]

Split off to it's own topic. Thanks JasonLion

Not to hijack the post, but my marble spillway where the spa goes over into the pool is rough like sandpaper - no visible bumps, but just feels rough. The PB is claiming it must be calcium scale (although he has not seen it). I know they just went to Home Depot and got a cheap piece of marble for the spillway because they cracked the original one and I think it is just being eaten away by the salt and chemicals.

So how can I determine if it is calcium scale? Wouldn't it be on the tile and plaster too? My pH has never been more than 7.8 for more than a day or two at a time. CH was high (400) for a bit but has come down to 370 after a few heavy rains.

How do you get rid of calcium buildup on plaster?

 

[JasonLion]

Treating marble is tricky because anything that can remove the calcium scale can also damage the marble. The risks are the same for any piece of marble, cheap or expensive.

Without knowing your levels, erosion of the marble from a low calcium saturation index is just as likely as calcium scaling. If you post a full set of water test results we can give you a much better guess at what might have happened.

 

[lborne]

OK, here are my results, and they have never ventured out of the -.6 to .6 csi range - not even close. Any idea what material would make a good spillway.

CL = 7
pH = 7.6
TA = 80
CH = 370
CYA = 80
Salt = 4700 (accidently added too much - should be 3500)
Borates = 50
Temp = 88F
CSI = -.25 (from pool calculator)