My P. shrimp are doing a good job on my Aiptasia problem. I was killing about 10 to 15 or more everyweek and that number is down to about three a week, but, lol , in my overflow box ( this box is inside my tank with a piece of PVC pipe in the drain hole with an open end at the top of the pipe the water drains into and then down into my sump, you know the kind) anyway there are a bunch of Aiptasia in the over flow box. What I was thinking about doing is getting a piece of nylon screen covering the top of the PVC pipe and useing a nylon tie strap to hold it in place and then putting a P. shrimp or two in the overflow box. Good idea or a bad idea, or should I just forget about them?? The thing is, with the canopy on the tank it really would be a pain to keep tanking the canopy off to kill these things.