Buba
I run 4 of them
1 x 200PX
2 x 150PX
1x100PX on a 300G Display system.
Some are for skimmers , yes that's plural.
others are for water flow...
The tank temp goes with the room temp. If the room gets hot the tank gets hot. If the room is cool, the tank is cool. The tank is at work so the room AC actually makes the heaters work during daylight hours. The chiller is reserved for Sundays when the building AC turns off.
The lighting is 3 x 400W and 2 x 250W MH. With the canopy fans on, the above still applies.
When I compare them to my home system, I was running 2 mag drives and a sedra, and the chiller would come on a spring NIGHT!Basically, my answer is none noticable whatsoever in my situation.
HTH.
Oh and RE: your above post.. my 300 has 4 x 6200's in it. They are overpowered to handle the reef as it grows in, they are set at 30 and 50% I also put the overkill in simply for a burst every now and then to clean house. Going thru a 24 squarefoot tank with a turkey baster is like vaccuming your living room with a dustbuster... You won't find me doing it, hence the flip of a dial house keeping service

How hard are your Tunzes set, The detritus could just be a result of Poor flow dynamics with your rocks? Is the tank too mature to rearrange a few?