id go with soil if you dont have a timed pump. i think the RW is going to drain too fast unless you have time to water 2-3 times a day. idk man, if your using clones the whole proccess shouldnt take more than 2-3 months so the roots shouldnt have time to fuck with eachother too bad as long as the cubes are 6" apart. the rocks should stop the algea tho, keep a good eye on it and you should be alright. PEACE!