If you have not seen the Youtube videos that MHPGARDENER published, they are great. I really like the one of his "off grid" or no electricity (ie, no air or water pumping required) Kratky raft system for lettuce. If you have some spare time, he has a lot of videos and they are very informative examples of greenhouse and hydroponic work.
I have the parts to make a summer Kratky grow box and wanted to try running one under T8 flourescent lights in the unfinished basement during the heat of the Georgia summer. Just need to put it all together and see how it works. Sure would be nice to have fresh lettuce in the heat of the south!
This is MHPGARDENER'S video on the Kratky method of growing lettuce.
An updated video....
Ned....Love it....your float bed....is it aquaponic [ raising fish and using the water to fertilize the plants ], or do you fertilize the water? I have a local farmer who has 3 old corn cribs [ holds dry corn on ears ], gonna see if he will sell them cheap. Gonna cut in half and make greenhouses, one for big fish tanks, another will have a float bed. 10 x 20, will hold a lot of fresh lettuce and will be fertilized by the fish do-do. Yep... gonna do that before I die...
I just fertilize the water, it holds 100 gallons, so mixing the fertilizer is a breeze. I think the fish idea is really cool, its a little more than I want to get involved with, but still I think its really interesting. I've always wanted to try lettuce in the float bed, but I've just never got around to it. Those corn cribs sound like a plan to me! The thing I've learnt about the greenhouse is that everything requires 10x more work than it seems like it should!
There is a company in our town here that grows plants, and Tilapia hydroponically . Google Volcano Veggies Bend Oregon and check it out.
I really like the Kratky method I wish I had more room indoors to try some of this out.