Crusty stuff on tile


Gold Supporter
Dec 26, 2019
NE Oklahoma
Alright, I have noticed some white crusty stuff starting to build up on just a couple of the tiles under my spa spillway. Odd that it is only in a couple of places. Can anyone advise on what this is and how to remove it? Brushing does not work. It feels scaly, almost like a calcium buildup. Odd that it is only in these couple of spots. Getting in the pool to clean it is not out of the question but holy cow, it will be a little chilly!

Edit - Added test results:

FC - 6.5
PH - 8.0 (added acid to bring back down)
TA - 80
CH - 450
CYA - 60
Salt - 3400
CSI - 0.16
Temps - 62F (water)

Tile Crusty 1.JPG
Tile crusty 2.JPG

We also had a nice afternoon today, temps in the mid 50's (colder than it has been the past week) and sunny, so I took the time to clean up the electrician's mess they left. It is insane to me that people are ok with this kind of workmanship. Not only customers, but the tradesman. Take pride in what you do, man!

Electrician's mess.JPG
Much Better.JPG




Gold Supporter
LifeTime Supporter
TFP Guide
Oct 25, 2015

I have a very small amount of this on my pool only under the spa overflow from time to time. First time I rubbed and rubbed with brush to no avail. Then added some muriatic acid then rubbed with brush and it worked but still difficult. Last time when I was cleaning the deck around the pool with a power washer I hit it with the wand about 6" away. Blew it to smithereens instantly. No damage to tile or grout but I was very careful to avoid the grout.

I hope this is helpful.

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