Mysterious Tile Deposits

[spoonman]

Last week I cleaned my waterline tile with a scrub pad and tile cleaner. The tile had minimal scale, so my goal was to keep any scale from getting worse.

A few days later it now appears that there is actually more scale at the waterline than before I cleaned it. I'm puzzled by this because I've been keeping my pH and CSI in range.

Could it be that some of the scale from the grout lines redeposited on the tile where it is more visible?

 

[Richard320]

Does it look anything like this:

I lifted that image from Calcium Nodules in pools

 

[spoonman]

No, more like a white ring right at/slightly above the waterline.

 

[JoyfulNoise]

No, more like a white ring right at/slightly above the waterline.

Like a white ring all the way around the pool?

 

[spoonman]

Exactly!

Curious why the ring appeared more prominent after cleaning the tile. I'm thinking maybe I removed calcium from the tile only to have it reattach days later.

Wondering if people use a sequestrant when removing scale so it doesn't reattach.

 

[pooldv]

That is calcium scale. Lower your pH to maintain your CSI between -0.3 and 0 to prevent scale. The ring will disappear on its own. More here, Pool School - Calcium Scaling