Lettuce DWC
Here's a tank I built to grow lettuce using Deep Water Culture. It's made from 1 inch blue foam. You can buy 2' x 8' sheets of this foam at Home Depot for about 7 dollars. Each sheet will make exactly two tanks. They are 24 inches long, 16 inches wide and 4 inches deep. The 3 inch holes for the pots are spaced 8 inches apart each way. Foam is great because it keeps the nutrients "warm" at night and "cool" during the day (relatively speaking). The foam is cut using a long-bladed utility knife. The tank is assembled using a low heat hot glue gun. Don't use a high heat hot glue gun as it will melt the foam. The lid is not attached in any way, it simply rests on top.
A single air stone -- a mere 44 cents each at Wal-Mart -- aerates the nutrients. I use a 3/16 inch stainless steel bolt on the air line to keep the air stone submerged. The air pump has two outlets so can power two tanks and are $10 each at Wal-Mart. A channel is cut (in this case burned with a soldering iron) in the top edge to accommodate the air line. The nutrients are used at 1/2 strength and supplemented with 1/2 tsp. per gallon Magnesium Sulfate (Epsom Salts). The tank holds 4 gallons.
I've eaten several salads by this time by trimming off the largest leaves as the plants grow.
Thriving roots.
The nutrient level should be maintained at about 1/2 inch above the bottom of the net pot (the bottom 1/2 inch of the pot is submerged in the nutrients as illustrated in the Tank dimensions below).
Tank dimensions
Questions or comments? Please contact me here: grass_man@oocities.com