Is it bad for shock to sit on the bottom of the pool?

Yes, it is bad to let the shock sit on the bottom of a painted pool. As it ionizes, it will eat away at the paint. Since the Calcium Hypochlorite has a low solubility, I recommend to my customers that they first dissolve it in a bucket of hot water, then pour it into the pool. That should solve your problem.

I ageree with previous answer. If using 'calium hypochlorite', dissolve in bucket of water, as best you can, but you will have a residue. Throw the liquid into the pool and toss the residue away (calcium, not needed in your pool).