I had similar issues when I first set up my BP system. The key, should you decide to try again, is regulate the flow of water to the rockwool cube. If you flood the cube with water it could certainly get too wet, tom makes a good point, and to be honest, I find the feeder tubes are most valuable once the sprout is established and less before (I usually adjust my water flow accordingly, very slow at first, then increase slightly till their feet get wet, then I remove pump). My reasoning being that once your sprouts start to get bigger (but before the roots hit the water) the cubes will start to dry out faster, now you can adjust a plain DWC system by making sure there is a good level of water agitation in your res, or you can let the feeder tubes do the work, both ways will work. IMHO. Good Luck!!