Vinyl Pool and Calcium

[iwannapool]

I've seen it said that a vinyl liner pool doesn't need calcium, makes sense. But I have also read if you have a heater and a vinyl liner then you need calcium.

Why does the addition of a heater require calcium?

[CarlD]

I've seen it said that a vinyl liner pool doesn't need calcium, makes sense. But I have also read if you have a heater and a vinyl liner then you need calcium.

Why does the addition of a heater require calcium?

The only reason I know is that the warranty requires it.

Other than that I can't think of one good thing it does.

[anotherpyr]

I've seen it said that a vinyl liner pool doesn't need calcium, makes sense. But I have also read if you have a heater and a vinyl liner then you need calcium.

Why does the addition of a heater require calcium?

Doesn't the heater put metal in contact with the water?
Does the lack of calcium cause the water to become corrosive?
Will this result in the heater failing prematurely?

If so, then that is why the manufacturers warranty requires it.

[iwannapool]

Interesting that you brought this up. I just got around to measuring both my inground fiberglass spa and IG vinyl pool CH last night. The spa was filled with my city water and the pool was filled by trucked in water. Both measured CH=0 and TA was ~125-150.

Not sure if I should add calcium chloride to raise CH or not for the pool equipment since vinyl and fiberglass don't require it. I know for sure my house water is very hard due to lime and I highly suspect the trucked in water is too.

[anotherpyr]

I run a vinyl pool without a heater and I've always been told that the CH didn't matter since I didn't have a heater. Of course if it gets too high and the saturation index goes over 0.3 you'll get scaling.

The Pool & Spa Water Chemistry guide which came with my Taylor test kit says that if the saturation index drops below -0.3 then it may cause corrosion of concrete and possibly metal surfaces.

So its more a question of how risk adverse you are. If possibly keeps you up at night, then add it and get a good nights sleep. It hasn't kept me up yet. But I do wonder about it occasionally.

Turns out there is an interesting conversation on this subject in this post http://www.poolforum.com/pf2/showthread.php?t=6891.

[iwannapool]

In my situation I have plenty of lime in the water but no calcium. Would the lime act as the calcium would for protecting the metal in the heater; if calcium can and really does that?

[anotherpyr]

In my situation I have plenty of lime in the water but no calcium. Would the lime act as the calcium would for protecting the metal in the heater; if calcium can and really does that?

Lime is calcium.
http://en.wikipedia.org/wiki/Lime_%28mineral%29

[iwannapool]

Interesting? So why when I test for CH I get zero? It seems as if this test doesn't recognize it or ? I'm lost !