Thanks for your suggestions! I partially drained the pool yesterday and am re-filling it with fresh water.
I have an automatic chlorinator so would like to continue using the tri-chlor tablets that I recently bought at Costco. I live in Hawaii and a 3 quart bottle of 6% bleach is $2.50 at the supermarket! The pool stores here do not sell liquid bleach, only granular and tablets. So do you think it would be a good idea to use a combination of the tri-chlor tablets in the chlorinator, and then once a week (or should it be more often?) add a 3 quart bottle of 6% bleach to the pool ? It is about a 30,000 gallon pool.