Hi all I am new tothis forum thing.Been helping with a marine aquarium for about two years now. My colleage left and left me the aqarium. It is in our office, open all round and was meant to calm the bad tempered atmosphere in the office. It works great. Had no big living thing in it but lots of red "grass" and coralline algea has grown. I once or twice saw a bristle(fire?)worm and quite a few very small brittle stars. I now added a brown tang of about75mm and a white short spike urchin which is cleaning up the grass and corralline algea better than a garden service my lawn. Over the weakend the heater faulted and tripped the power. We only noticed it on Monday morning when the temp had dropped to 16degrees C. I put a spare heater in and 3 -4 hours later the half frozen tang was swimming around again. What I would like to know is if I put another heater in the sump, would the characteristics change a lot. I have some white wormy thingies in there.