Ph problems!!!

why is my ph keep rising?
my plants are 4weeks and they are dying!!!!!!
using 150w hps lights, airstone
and i have the temperature perfect


i adjust the ph and after an hour it goes up to like 7 even 8

Look for dead things (peoces of root) in your res or gunk on your airstones.

On another note,using an HPS for veg is doable but not optimum. Wrong light spectrum. You can consider adding some cool white (6500k spectrum) cfl's to augment the HPS (around 2700k spectrum) for better veg growth.

Hey roll... need a little more info.... what type of grow , nutes, h202, water source, etc.