How would this work?

[Reefmaster]

adam i hear ya on this.
my opinion is the idea itself is a good one, use nature to rid excess energy in your system. saves energy on the fans and the g.d. noise they produce.
there was someone on the net with a large system (was it john rice?) who decided water was cheapter to buy and waste than electricity, fans etc., so he had a thermostat controlled cold water line that coiled through the sump and dumped down a drain to cool the tank.
i like your idea and have considered something similar, but for our system we would need a two stage control device to turn off the heaters and then turn on a pump and v.v., but this control is about $130.

[ 30 December 2001: Message edited by: Reefmaster ]