My pool builder was out yesterday installing a conversion kit for my filter system. During his visit my wife filled him in on our use of the BBB method. He was not opposed to it (BBB) but relayed a caution/warning about using muriatic acid. He stated that muriatic acid in vinyl pools can cause two specific problems 1) damage to the liner and 2) costly damage to the heater. This post in not intended to malign my pool builder I'm sure his caution was given with the best of intentions. I was wondering if there is any validity to his statement and if so what alternative would be available.