Calcium???

[waterbear]

I have been researching this also and have found nothing difinative in whether calcium is needed in a vinyl pool but there is some evidence that it MIGHT be needed in a fiberglass pool to help prevent colbalt leaching from the gelcoat. I have also seen some suggestions that calcium can help contribute to pH stability in conjuction with the TA but the chemistry was rather muddled so I am not at all sure it is valid.
EDIT: If there is a manufacturer's warrenty involved then I would add the calcium to the level they recommend to maintain the warrenty. It's not going to hurt anything.

As far as anti acids go---they neutalize 37 times their weight in excess stomach acid!