i am still using one despite al of the "problems". As soon as i heard that there were problems i switched out the velocity pump that i was using for another velocity that was a backup(NIB). i took apart the pump that was in constant operation for a year and a half and all i found was a dead snail shell in the impeller and the back of the impeller was encrusted in calcium. I soaked the calcified parts in vinegar and put it back together and everything works fine, not that anything was wrong to begin with. i have had no problems with these pumps and maintaining them is easy and quick. the only thing that i could see being a problem was the calcium scale growing to impede thermal conductivity between the water and the housing causing the pump to overheat(in addition to the calcium scale titanium is not a very good conductor of heat anyway). but these pumps are thermally protected and would cut off before the pump burned up, but would turn back on after it cooled down. this on/off phenomena would probably be pretty obvious and easy to fix if your plumbing system is put together in a fashion that you can extract parts with ease for periodic maintenance. IMO these are good pumps and are EXTREMELY quiet too.
I am using the T-4 on my 120 sps tank. I switched it out and love the quiteness of this pump. I did this after setting up my 180 ecosystem reef tank and like it so much on it I wanted to go ahead and use it on both tanks.
