which brand of heater would you recommend?

[midgetwaiter]

I can't recall each case, but one that does stick out in my mind was a 125 gallon tank heated by two 200W heaters. According to the owner, only 1 heater failed, and by the next AM his tank was cooked. Of course this would depend on the ambient temp of the room, the temp that he normally kept his tank at, and the amount of surface agitation in the tank, but still, one wouldn't think that a single 200W heater would reach such high a high temp overnight in a 125 gallon, but I guess that in this case it did just that. He lost a large whack of adult fish.

Ahh good point about the oxygen levels, I didn't consider that.

Just so everyone else can follow what he's getting at here a modest increase in temperature can still cause you problems. As a liquid heats up it's capacity to keep dissolved gases in solution diminishes (Boil's Law). If we have a case where there is an increase in temperature from 80 to 85 the heat won't get the fish but the oxygen level in the water will decrease significantly. If this happens on a tank that is filtered by a couple of canisters that are not setup to provide some surface agitation and also contains some large fish that are not accustomed to lower oxygen levels you're in trouble.

[RD.]

Yep, the poor sap in the link below lost an entire colony of tropheus from lack of 02, as the temp was only 88F when he found his fish floating.

http://www.cichlid-forum.com/phpBB/viewtopic.php?t=84417

It looks like he has since removed the second pic in that thread, probably best, it wasn't a pretty sight.

[Willfishguy]

Eheim Jager, Jager, Jager, Jager! Thaaaaaaaaw best!