Calcium hardness for SWG/vinyl pool with new fiberglass steps


Active member
Jul 14, 2017
Blainville, Qc, Canada
Just changed liner, steps and skimmer after 15 yrs. I’ve always run with CH between 50-100 (not added, just whatever fill water and shock produced). However, the new steps are fiberglass. I was wondering if that meant I should now start keeping my CH in the 225ppm range to prevent affecting these new fiberglass steps.
Sgt Wilko


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Raising CH to 225 would not hurt. See ...



TFP Expert
LifeTime Supporter
Jul 21, 2011
Eastern Ohio
Increasing the CH won’t hurt anything as long as you don’t go sky high, except your wallet. That said, also won’t help anything either.

Years ago there were rumors that vinyl manufactures used calcium as a filler in their pools. To date nobody has been able to offer up a solid piece of evidence that backs this up really. Around the same a few individuals wrote multiple manufactures and asked flat out if they used calcium. All said nope. So for the steps. Again, years ago calcium was used as a filler in the gelcoat but most companies have stoped this process. It’s simply not needed.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
Calcium chloride has so-o-o many applications in industry it is the generic "kleenex" of has hundreds of applications.

When I worked with Dow Chemical, I watched them dump HUGE amounts into liquid acrylic fiber. It served as a brightener as I remember but it has myriad other uses.

I believe it tends to make plastic (vinyl) less flexible but is used as a "filler" to get more bulk at less cost into the product. So anyone could use it in the manufacture of a liner and I am sure they an extent. It's the extent to which they use it that may add or subtract to the flexibility of a liner.

I cannot see how this calcium chloride, even if it's in there, can be pulled from a vinyl liner but that is over my pay grade.

I would not be concerned about CH in a vinyl pool. Probably not fiberglass, either, but I am not sure.

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
I suspect the one issue with a very low CH in a pool with fiberglass might be the potential for staining. Cobalt staining is one type, but I suppose any mineral-based item would also be something worth watching. If your steps are white, you would probably see such staining color changes fairly quickly and could adjust accordingly. Most of today's FB pools and products are no longer manufactured with calcium fillers, so erosion as we know if from plaster pools, is not a concern.