Michelle:

Here's PoolDoc's final answer to the calcium and vinyl question:

http://www.poolsolutions.com/tips/tip03.html

Ben (PoolDoc) says that Professor Langlier himself say his index isn't relevant to pools, and one of the biggest manufacturers of vinyl used by the liner makers discounts the need for calcium as well.

If I were your friend, I would tell that store that if they don't take back sealed chemicals just purchased that she, and you will NEVER frequent that store again. You won't buy toys, accessories, chems you DO need, large items (like a solar cover or solar cover roller)--nothing, Nada, gornischt there--and you'll tell the 15,000 pool-owning friends you have (Us forum folks --but don't tell them that) not to use them.

If you have a floater in the pool, then simply add bleach to the skimmer and make sure the floater's not right at the skimmer's door. Once chlorine's in the water, it doesn't matter where it came from, but pouring bleach on the tablets could be very, very dangerous.