I had the same problem, hundreds of Aptasia of all sizes in a 90gal. 24" tank. Sounds simple to just shoot the juice to them but in reality kinda hard in an established tank where they are everywhere including under and behind LR. I tried it all also, nothing worked, to far overgrown. Thought about just tearing the tank down giving up or starting completely over that's how bad it was. One day I seen an add for the Berghia, bought 12 and they just disappeared into the abyss. Got up in the middle of the night just to check on them and I did see a few eating the smaller "weeds", my only hope would be they keep multiplying and rid my tank of the pests. This was not the case. Here's what worked for me, I turned off all lighting and quit feeding for about 2-3 months. I personally watched my Chocolate Star Fish devour most of the Aptasia out of hunger I guess. Fast forward I have been running my MH & T5 system 4-6 hr's a day now for 2 months and I see no sign of the "weeds", all my fish lived (didn't loose one). Yes you will loose most Corals, SPS, etc. but I didn't have to tear down the tank and start completely over. There is no easy way when they get out of hand................