I used the "pink stuff" to close the pool, but this year had a surprising amount of algae when I opened. Did everything the same as every other year, just purchased a different brand of anti-freeze (not automotive). I can't remember the brand but can look it up. Did anyone every link additional algae with RV anti-freeze getting into the opening pool water? I successfully vacuumed out the dead algae, but there was more of it this year than I can ever remember.