Just a note, that was a trial that became permanent. I have moved to Perth last week, so i will be looking at beautifying that setup a great deal!
I have found that succulents have been the best performing plants by far. Herbs/Veg etc require a lot more light than i have been able to provide so far. Although now i have my own place, i will probably revisit some edible plants.
I would like to try and have a nice inside grow bed that is not at the top of the tank. The plumbing shouldn't be too hard.
One thing to keep in mind, if you are planning on eating the plants, you cant use any aquarium meds. If the plants absorb any of the meds, then you are eating them too. I dont know about some of the more sensitive fish species, but with the more hardy tropicals i have kept, this has not been a problem. The only meds that i used for years was salt and i didnt have any problems.