Note one way to suck heat off a parabolic is to place alm. vent at the top of the fixture and use a bathroom 70 cfm to pump out the extra heat.
I used on with a suncircle with a 1000 watt MH and a 400 watt hps. The vent temp was about 15 degrees differance between room temp and venting temp.
The room was about 20% less time on a normal venting time.
I use a single bulb system now, as very little co2 get picked up by the vertical heat rising from the bulb. The tanks last about the same amount of time. A extra advantage to the heat pump is it warms up the grow room and clone space.