Steve,
I have the 24g Aquapod (open top, no hood) with the 150w sunpod.
Here are my suggestions after lots of experimenting.
1) Make sure the room is not warm...not going to have much luck keep the temp down if the room is 80 degrees. I had an issue originally because although my thermostat is set to 78, I kept the door close and that room got a bit warmer. I know keep the doors open and that room is cool.
2) If you are using the glass lid, make sure to keep the glass slid to the front so there is a nice gap in the back.
3) I have a cheap ($6) 4" fan from Frys sitting directly on top of a half sponge (from the original two sponges, I now have 4 that I rotate through). Think of it like a swamp cooler. I tried various positions of blowing the fan across the water, but since I needed the glass top on, I ended up going blowing air into the wet sponge. Since the warm water from the tank funnels through that one spot, I think it's also the most efficient. Not to mention, it's the least obtrusive.
4) I tried triggering the fan with a temp controller but found that it works just as well to hook it to the same timer as the sunpod. I've not noticed any sudden dips in temp.
With the above, my tank is stable at 78.5 degrees. My original temps were 83. I think you can keep the temp down to a half to full degree over the ambient temp of the room.
