A do-it-yourself idea to remove calcium?


LifeTime Supporter
Jul 12, 2010
Wimberley TX
After last summer's drought here in Texas, with our Austin makeup water being in the "moderately hard" category, my pool water's CH is now around 500. I have rigged a gutter drain to empty into the pool to try to capture as much calcium-free refill as I can during our spring (hopefully) rainy season.

Last year before I figured out what was going on (thanks to this forum!), I was getting white flakes (calcium) coming off the SWG fins and blowing into the pool. Now, with my ph under control, I don't have that problem, but I would really like to get the CH back down to 100 or below. I know that a reverse osmosis treatment would accomplish this (I am waiting on a quote, but it's probably expensive), as would a drain/refill of the pool (and that is really wasteful).

However, since the calcium would come out of solution and stick to the fins of the SWG when the ph was too high, I wondered if there is a way to re-create that effect in a home-made, recirculation device with more fins (separate from the regular pool equipment). The precipitated calcium would then be filtered out or captured before returning the water to the pool. Since the effect depends on the water's ph, you might have to raise the ph of the entire pool for a few days to get all of the water circulated and treated before returning the ph to the proper range and removing the device.

Anyway, is this just a crazy idea that would never work, or do any of you technical chemistry types think it is do-able? I am an electrical engineer by training, so building the electronics for the precipitator would be fun. Is the effect just hydrolysis, which would only require a DC potential? And, would this have any other effect on the water chemistry?


LifeTime Supporter
TFP Expert
May 10, 2010
SW Louisiana
I just wanted to suggest using some sort of filtering on the water coming off the roof, before putting it in the pool, particurly this time of year the roof is likely covered with lots of pollen and dust. Maybe a simple diversion valve would be good too, set to dump all water for the first few minutes of the rain before then filling the pool.