are you planning on leaving fish in the tank? if so, that is aquaponics. using fish waste to nourish plants living off it. if not using fish, letting light get to the nutrient solution will cause algae to grow. i like the aquaponics idea. i've done it with lettuce a long time ago with good results(high school science experiment). if your interested in aquqponics check this place out:

Aquaponics, Hydroponics Consulting, information, equipment, design, construction

i've never heard of aquaponics with marijuana, but this has got my mind going. maybe its time to start a new project. ifgoing straight dwc hydro, you can't have too much air in the nutrient solution.IMO. just look at other posts here on set-ups, they'll get you going.:thumbsup: