I thought I'd update on the hood's performance, because we're in the heat of summer now, and now is this upgrade's time to shine.
First off, JUST having the fans blowing over the water was not very efficient. The problem was that the fans would run until the water cooled to the point the heater kicked in... Keeping water temps within 3-4*F was getting expensive with a 300w Heater, then there was topping off the tank 2-3 times a week.
Modifications were in order. I purchased the Inkbird ITC1000-F controller, and set the controller up to switch the fans ON at 80*F and OFF at 77*F... the heater is set at 76*F. This set up is MUCH more efficient, causing a lot less evaporation in the tank, and eliminating the heater cycling. The ITC-1000F is a great piece of kit, but the temp sensor supplied starts going south after about 5 months. I switched it over to the 12" stainless steel temp sensor brewers use, and the temperature reading is much more accurate.
This set-up has been an interesting journey, but I think I've got it working as it should. In the summer, the water temp hits 80*F and the fans remain on till it goes down to 77*F, then the fans turn off. In the winter, the fans basically stay off, and the heater keeps the tank at 76-77*F. A 4*F variance year round is certainly acceptable, and the fish are all happy and healthy.
Necessity is the mother of invention... A happy community tank is the end result.
I would love to show pictures, but recent policy changes here have prevented that (photobucket). I tried to attach pics, but the web site kept dropping attachments... Oh well.