Posted 03 January 2002 - 10:01 PM
Any time you see a leaf tip turn brown its most likely due to over fertilization or salt build-up in the reservoir. Flush your syatem out and reformulate a new reservoir of nutes. Everyone has their own idea on nute strength and fert ratios, but use the one you feel most comfortable with.
I checked out some different forums and the general consensus is ph ranging between 5.1 to 5.9, with a average of 5.6 being the most common. I've seen other pH levels as high as 6.2, but I've never seen anyone recommend pH as high as 6.4.
TDS recommended ranges. Most forums recommend 500 to 1000 ppm for TDS. With the lower ranges at the beginning of grow and the higher end toward the beginning of flowering.
If the plants are healthy but show a fert burn begining, ease the nutes back and try lowering the pH slightly.
Good Luck, and I hope this was helpful