I bought what I thought was a BTA, as it looked very much like one at the LFS, but after some days of research, I figured out it really was an H. Mag. That made me quite worried, as I have heard they are the most difficult to keep anemone in the hobby. Well, I kept it, as I will only have it for another few months, as I must sell my tank then. It has been in my 20 gallon nano reef, with HOB refugium and skimmer, and has been doing very well. It is about 9" in diameter. The first week I had it, it attached to the side wall, and inflated and deflated daily, and it did not seem to be doing too well. Now though, after having moved it on a rock, it has stayed put for 2 and a half weeks, and has been thriving every day. It is under 4x24 watt t5's which are about 3" off the water, and the anemone itself is about 3-4" under the surface. So far, it has been doing very well, and I just want to show you guys that it is possible to keep an H. Mag in a small tank (until it outgrows). Enjoy...