GMSgrowsanswered grow question 3 years ago You should be running them at 5.8 ph and from the time they are born I feed at 400 ppm for new burns and every week I increase by 100 ppm as long as you see good growth. Stop when you reach 800 ppm. Your water is best kept at 62 to 68 degrees to have maximum amount of oxygen in the water for your roots. A good heavy air stone in each bucket. If you haven't got a chiller then frozen water bottles around and in your rez to keep your water cool. 5.8 ph Is the perfect setting for veg and 6.2 6.3 for when their in flower. Run some 5.8 ph water over your rockwool and clay to make sure your medium is properly ph'ed.