Different heater brands list different tank sizes based on wattage, guess it all boils down to efficiency and design/placement as well.

ie Aqueon 250w Pro heater is rated for aquariums upto 90g, where as Eheim Jager at 250w is rated for 106g - 159g

I think I'm going to get in the habit of changing heaters every year they pretty cheap and for how important they are probnalu worth it

I keep my tank at 81 degrees and my room temp is 21 Celsius both controled by reef keeper they seem to do the job

my understanding is that you have to take the ambient room temp into consideration. Once you have the proper heaters for the size of aquarium, the heaters only increase the tank water, 10-15 degs above the ambient room temp.

I found a chart on line. Scroll down to bottom of page, under ambient temperature.

http://mayerspet.com/?p=1010

I have 4x 200w Jager's on 300 net gallons. (415 gross gallons just counting tank glass sizes)

I have set 2 heaters each on 2 temp probes. The system stays stable with 3 heaters but not much margin for failure. I figure with 4 smaller heaters one can fail ON or OFF and not cause me any grief.

That chart puts me right where I want to be with wiggle room
Ambient is 74 and tank is 79, so my third heater is a failsafe

I've always run closer to 5 rather than 3 watts/g

Does the chart take into account the dumbass coefficient??

Anyone ever recall reading about my chiller being plumbed outside. With PVC. Outside? Mhmmm.

Are you able to take that offline easily and drain the pipes?

No, I'll just have to wrap the pipes.

[IMG]http://i1343.photobucket.com/albums/...psb779d99a.jpg[/IMG]

I have one Aqueon Pro Aquarium Heater (250 Watt) rated for 90 gallons my total system is about 190 gallons.I have it set to turn on at 78 to slow down the heat loss. One advantage to 800 watts of Metal Halide lighting it will keep your tank warm during the winter. I have two 150w that turn on at 11:00 and two 250w that turn on at 1:30 as soon as the temp hits 80 the apex turns on the fans. I only have to run the chiller in the summer . My temp fluctuation is between 78-80 each day. I know some people will say that to much but the corals seem happy.

I use 2 x 250 watt Jagers on my 165g . Plus I have an old 125 watt stealth in my 55g refugium.