I took a couple caps DT's and added it to a 10g with about 3/4 old tank water, put a light on it, a bubbler,and some miracle grow and wah-lah! I ended up with a few pods and brine shrimp growing in it from the old tank water too.
Its not the most sterile way to do it, but It seems to be doing well, I have yet to get it dense enough to use it yet though.