the only safe powerhead is a broken one... The only time when I left on a weekend trip was when my green BTA decided to move. Not only that, it somehow got up, over, and in my powerhead guard. I had the hagen 402 upsidedown in the upper corner of my tank with a home made plastic strainer to anemone proof it. When I returned from Boston three days later, I had anemone soup. I tested my parameters and it must have happend 30min to an hour before I returned home because I had 0 ammonia/nitrites. A large amount of waterchanges later and a nap, the tank was about to begin a long fight with cyano, since I wa ssnever able to remove all of the anemone pieces and had high amounts of anemone nutrients. Alhough I dont want to discourage you, I think I am going to get some SPS next. I just can loose another anemone and risk the tank. I guess if you search the forum you can find some good ways to anemone proof your powerheads (better than me). I know someone had a thread that said "show me you covered powerheads" or something. I would find it for you but its 3am on my final exam week and I need some sleep. Goodluck