Katie....First up: CONGRATS on freeing yourself of the Baquacil product !! I did the same two years ago and have saved literally thousands of $$$$.

If I remember correctly, I believe I kept high levels for 4-5 days AFTER my overnite chlorine loss subsided....plus, with the amount of bleach you've gone through already, whats another few gallons to be on the safe side...

DEFINITELY change out your sand....the Baq. residual that was trapped in my sand was astounding....again, not really a huge expense to purchase another bag or two....(just think of the $$ you spent on Baq Sanitizer alone)!!!

FYI: If the pool store says don't change....that really means DO change !!!!....

Congrats again....you'll never look back !