I love this. I was going to do something similar in my cubicle but the noise level was unnacceptable for a quiet office environment.
I just have a couple of suggestions.
1) Look into and consider a constant flood system. This will allow you to keep your tank full so the aquarium water level doesn't fluctuate so much. You would think that plants wouldn't do so well but in my research I found a long forum thread where someone did an experiment with 3 different aquaponics systems and the constant flood did slightly better than the flood and drain, which was surprising to me.
Aparently the water is so oxygen rich that the roots don't need to "breath." Anyways, you might want to look into it your self.
2) Cover your tank. You have to add a glass of water everyday? That's a lot of evaporation, and seeing that your tank has a larger surface area than the grow bed, I think you could cut down a LOT of evaporation by covering the tank.
I also had a question. What are you using for the media in the grow bed? Is that the expanded clay balls? Regardless of what it is, how heavy is it?
I may turn my 150 gallon into an aquaponics in the future, but once concern I have is keeping the weight of the growbed to a minimum. Regular pee gravel just seems way to heavy to me.