Currently, their indoor system grows mostly lettuce planted in a really great looking system of floating foam panels (called a floating raft system) with holes cut in. Looks a lot cheaper than using a full bed of growing medium. Mark suggested having a good 18-24" of water depth below the rafts. The lettuce is planted in a small plug of shredded bark, and grows in about 40-45 days. The fish come from a local research facility (I think associated with UWM freshwater sciences program) so they get the little guys for free, and sell to high-end restaurants in the city. At their little store the perch was selling for $18/lb...
A lot of their current costs seem to be going towards artificial lighting (mostly high pressure sodium), so they are also building an outdoor system with greenhouses for the plants, and a very well insulated shed for the fish. In this system the water is gravity fed from the fish tanks to the plant beds (through a screen drum filter to pull out solids for compost), and then the filtered water heads to a sump tank under the fishery.
Summer: lettuce likes it cool - need to find ways to keep greenhouse cool.
Winter: Need to keep water warm enough. DIY solar hot water?!
Pesticides: they use Ladybugs!
Our awesome tour guide, Mark, is actually a water specialist by training, and would be happy to talk to us in more detail. Also, one of the founders of Sweet Water is a local roofer by trade who did my parent's house back in the day. He also went to Wash U (ABD in Philosophy!) and may be up for discussing 'stuff'. I will get in touch.
In the mean time, check out my pics: