It's listed as an algecide, but has gotten some pretty good reviews as a water bug (backswimmers, boatmans, etc.) killer. I've noticed some water bugs over the last few weeks in my pool and netting them out is just not effective bc more are right back in the pool the next day. So I decided to give it a try, it called for 9 ounces (startup dose) for my pool but I only used 6 ounces (I always use less than what's called for when trying a new product just in case I don't like it). I put it in yesterday morning and was expecting all the bugs to be dead today, but I still noticed them swimming around this afternoon. Maybe I didn't give it enough time to work effectively? Anybody knows how long it takes to kill them off once put in the pool? Maybe I didn't put enough, but I'm guessing I didn't give it long enough time to work?