I called Taylor today to finally ask them why they recommended a minimum CH level of 150ppm for a vinyl pool. I spoke to two people before finally being directed to a third. He said that even if the calcium didn't come from the vinyl, the water would try to pull it from somewhere. I said that most everything is PVC and fiberglass - in that case, why the calcium? If water is getting onto the pump motor, you're in trouble regardless of the calcium levels.

His two responses were that it could pull calcium from behind the liner (what?) and that low calcium levels made it difficult to balance pH and Alkalinity. Is there any truth to this? If not, the misconceptions must come from somewhere - does anyone know where?

Thanks any who take the time to answer, as always.

pulling calcium from behind the liner wow

The only argument I have ever heard for maintaining a certain CH level in a vinyl lined pool is due to warranty requirements with the equipment attached to the pool, iff applicable, like heater etc. Other than that I would ask that rep for his source.

Low calcium levels making it difficult to balance pH and Alkalinity??? I think they may mean that if you wanted to get to a zero saturation index, then a low CH would require an awfully high TA and pH combination, but that isn't the point. The question is whether a low saturation index matters in a vinyl pool. I haven't heard any reasoning from them (from what you wrote). I'm surprised they didn't use the argument about protecting against metal corrosion (which is debatable and unlikely -- see this link).

On this page they mention that low CH can have an effect on grout as well as the deck concrete. So even if you have a vinyl pool, there could be other things that are susceptible to calcium corrosion although it would depend on the exposure of those surfaces to the pool water.

Yes, we usually say something like "plaster or any exposed grout in tile". I hadn't considered deck concrete, though rain water wouldn't be good for such concrete either so similar sealing precautions are probably needed in that case.

In a hot tub, having some CH helps reduce foaming. Pools don't usually have the massive aeration of a hot tub though.
--paulr

http://www.swimuniversity.com/water-che ... -pool.html

Web page ad

yeah...notice the recommend products...I do know but I doubt soft water speeds up the breakdown process of vinyl.

Low calcium levels do not bother vinyl pools at all. Concrete, plaster, tile, pebble, quartz, gunite, grout, natural stone surfaces, and to some extent fiberglass can all be damaged by low calcium levels, but vinyl is just fine.

The reasoning they give for adding calcium to a vinyl pool is the following:

Calcium hardens the water so that it doesn't penetrate the walls of the pool and eat away at the vinyl liner? This makes no sense whatsoever. Now if you had a leak in the vinyl, then if the water was exposed to concrete it could slowly dissolve the concrete, but again that requires a leak in the vinyl liner. Also, unless the leak was rather large, any dissolving of the concrete would quickly saturate the water near that concrete and the dissolving would stop. It's only if there were good water circulation with the rest of the pool where there could be a problem.