I'm about 4 weeks into veg and have been having issues with the bottom leaves yellowing, drying out and then dying off altogether. I'm using 400W CFL and "Compo Sana" soil and I water them with filtered water. When I first posted with this issue people said it was nute burn, but I flushed the plants twice already and it just doesn't seem to be getting any better. I'll be buying a pH-meter in the near future so I can more accurately determine the pH of the runoff water (it's a little high right now...right around 7). Other than the bottom leaves the plants seem to look like they're doing really well. Any tips or suggestions?