Is this calcium scaling?


LifeTime Supporter
May 9, 2010
Hi all! Have a few quick questions for the good people of TFP!

If you would like the history of my pool, you can see this thread:

I had previously seen some odd patterns on the walls of the pool while draining it. These patterns where identified by some TFP folks as calcium scaling. I accepted this as reasonable due to the EXTREMELY high calcium level the previous owners maintained (like 800+ ppm). Here is a picture of what I saw:

A few weeks ago, I added borax to bring my pool up to 50ppm borates. Several days after adding the borax, I noticed some dark "blotches" on the bottom of the pool. I did not notice these before adding borates. I've tried to take a picture to show here, but my camera has a difficult time focusing through water. Here are a few pictures:

Hard to see on this picture, but they are to the right of the step.

I've tried brushing with both a nylon brush and a wire brush. I also tried scrubbing with a Scotchbrite pad, none of which seems to help.

Do you all think this is the same calcium scaling I've likely always had? I'm curious why I wouldn't notice the blotches until after I added the borax. Perhaps they change the surface tension of the water?

On a related note, since I've wrangled the chemistry into an appropriate range(3 FC, 7.6pH, 70 TA, 40 CYA, 340 CH), I've had constant pH rise with no aeration. Could this be caused by the calcium scalling?

Thanks all!


I didn't see your earlier post (the one you linked to), but I did catch this one. That being said, yup, that is calcium scaling. :cry:


Well-known member
Feb 10, 2008
Gilbert AZ

I have a similar problem. I assume that the gray/tan is the calcium and the white is the plaster. Would that be correct?


Sure looks like it. You have a pretty good build up on your tile line also.
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