Calcium or no calcium in a liner pool?

rawb

Bronze Supporter
May 3, 2017
147
Lexington, SC
My PB is currently doing the initial balancing of my pool and plans to pour both a bag of alkalinity increaser and a bucket of calcium in the pool for the next 3 days. I'm not sure what target levels they are going for but wanted to get some opinions on whether I should or shouldn't put calcium. Looks like TFP Pool School says it's not need for a liner pool, but then found some other non-TFT articles making a case for it in liner pools for various reasons but recommended only about 100.

Thanks in advance!
 

borjis

LifeTime Supporter
Aug 19, 2014
3,032
Pacific NW
Do you have a heater?

Allegedly it is a good thing to have calcium to adhere to heater mfg suggested chemical levels for the warranty.
though they also say no chlorine above 2-3 ppm which most of us are above.

I used to be a bit of a calcium cop pointing out the heater argument, but now
I don't add calcium at all. I still test for it, but don't buy calcium to add.

Probably fine without it, but let the installer do what they are doing so they
cannot deny any warranty work, should it arise.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,016
Tucson, AZ
Do you know the calcium hardness of your fill water? As long as your CH is somewhere around 200ppm, that’s good enough to satisfy most warranties. If your CH was below 100ppm, then you might get foaminess in your pool water since the calcium helps to breakdown foam. The foam would be caused by oils in the water from sweaty people or folks that like to apply thick layers of sunblock or tanning oils.

There is no definitive evidence that low CH causes vinyl liner problems. It is simply assumed that because vinyl liners contain some amount of calcium carbonate in them (as a mechanical filler/modifier and white colorant) that low calcium water would leach calcium from a liner and damage it. That’s simply an unproven assertion and current evidence would seem to suggest that CH is mostly irrelevant for vinyl liners.

As for heaters, that’s an argument taken out of context. Yes, in boiling water steam generators and commercial steam heating systems, the calcium hardness of the boiler water is always adjusted so that there’s a positive scaling potential and a thin surface layer of calcium carbonate is deposited to protect internal metal surfaces. This is not at all the same situation with pool water heaters but, like a lot things, the concept got borrowed and misapplied by the industry. pH is a far bigger determinant of heater corrosion than CH will ever be but the industry is stuck on having higher CH levels so there it is. Maintain your pool water CH above 200ppm and the heater manufacturers will be happy.
 

PoolguyinCT

In The Industry
Jul 21, 2014
3,083
Connecticut
“There is no definitive evidence that low CH causes vinyl liner problems. It is simply assumed that because vinyl liners contain some amount of calcium carbonate in them (as a mechanical filler/modifier and white colorant) that low calcium water would leach calcium from a liner and damage it.

That’s simply an unproven assertion and current evidence would seem to suggest that CH is mostly irrelevant for vinyl liners...”




The “assertion” will be explored in about 2 years. & it’s going to be combative, as there is no definitive “vinyl.” & only regulated the “landfill”
EPA level.

As I watch the “landfill” regs become more stringent I see the change in performance follow.

Vinyl is surely not what it used to be, failure, service life, failure types & longevity are definitely changing..

Anyway OP - 200 is nice place for your liner pool cal..