Calcium Staining


May 17, 2010
I am getting some calcium staining at my waterfall. Prior to draining my pool to 30% I had a CH of 420. I got the CH down to 360, I guess my water must be pretty hard. After a couple of weeks the CH has returned to 420. All other parameters are within BBB parameters. I have only been using bleach with great results after adding borates (50ppm). I cannot think why the CH should be rising. I will test my tap water when I get home, that may be some of the cause. Maybe the summer temps have something to do with this.


Well-known member
Mar 13, 2009
Your fill water is likely the issue. As far as the scaling goes, pools that have water features normally battle high PH. High ph can cause calcium to fall out of the water and deposit on your pool surfaces.Low ph can disolve your plaster. For these reasons its important for plaster pool owners to use the csi tool in the pool calculator. I am sure jason or richard will be along to remind me there is much more to it , but I am at work and really dont have time for a well formulated response that would make them proud :lol:


May 17, 2010
The staining though not heavy seems to have got worse since adding the new water. The deposit is on the natural stone rather than on the tile.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
I cannot think why the CH should be rising.
Hi, Mike,

Evaporation. As the pool water evaporates, the CH stays put, when you add fill, more CH comes into the pool and can't get out (unless you splash it out or drain.

Measure you CH fill water. If it's down aroun 200 or so, drain a little of your pool water prior to refilling (maybe a foor if you can stand the water loss). That'll help keep your CH below 400.

Remove as much scale as you can mechanically and then try a 4:1 mix of water/muriatic acid on the rest of it. If it doesn't foam up when you apply it to the scale, it's not strong enough.


LifeTime Supporter
Aug 4, 2009
i live in parker, tx right down the road and have the same issues. My CH is at 410 and I can't seem to get it down. I have read to try and keep CSI in the negative to reduce future scaling. Do you also have issues with keepin PH steady? I have 50ppm of Borates as well.


May 17, 2010
Evaporation makes sense. The calcium line is where the stone absorbs the water then evaporates leaving the salt. I will try the muriatic acid and test the tap water. Modog, my pH keeps rising but not too bad. I reduced the TA to about 90, I go through a lot of chlorine though. The borates is the only thing that seems to keep my algae in check even using bbb.
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