what kind of ph levels are you running? hydro sounds real cool when you tell yer friends, but for a beginner i would say try a grow or 2 in soil, if you cant get a weed to grow in dirt then you might want to find a good connect. 400 watts might be on the small end, or too far from plants <stretch>, is it a grow light or security? city water has chlorine among other crap that is not in your plants best interest, don't worry it sounds like a lot to worry about, it is, but when you kill off a batch, u can try again, enjoy