High hardness and what appears to be calcium deposits on plaster

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Drew80

Drew80

0
Feb 26, 2013
337
Austin, TX
I have three issues.

1. Really high calcium hardness. I just measured it at 850. I replaced the water last summer, and I balanced it out to around 250. I know that I need to drain to get the CH down, but why would it have come up so much?

2. I am getting white spots on my dark blue plaster (Image here). I can pick them off with my fingernail, so I assume it's calcium deposits. How can I get rid of these?

3. I also have spots of discoloration around my pool furniture (Image here). This appears to be some sort of deposit as well.

I'll note that my pool was brand new in early 2018. Could the CH just be balancing itself out over time? Am I doing something wrong?
 
Then you have been adding calcium somehow.
Do you use any powdered 'shock'?

Only other way is your CSI has been very low (very low pH and TA) to make your water aggressive to your plaster.
 
I have a SWG and use bleach when the chlorine levels get overwhelmed or it gets cold. No powdered shock at all.

My pH and TA both run high. I measure pH every week - it's usually around 8 and I bring it down to around 7.2 with muriatic. TA is consistently in the 300+ range.

My pool builder walked the job half way through and I was left to fill the pool for the first time myself. I screwed it up and had staining/mottling all over my plaster. I did a chemical treatment (Jack's Copper and Scale) last summer to remove the mottling - maybe that pulled calcium out of the plaster and it's just been high ever since?
 
Last edited:
As the treatment was used to remove plaster, that was it. You need to exchange or drain/refill about 75% of your pool water.
 
An acid wash will remove more plaster and will reduce its life dramatically.

If they are not very bad, replacing the water and running a slightly aggressive to plaster water chemistry should remove them, over time.
 

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