Hello: I am currently growing in coco. My plants are a couple of feet high and in in the 3rd week of flower stage. Some indica, some sativa. They are in two gallon smart pots. I water with nutes every 3 or 4 days when the pots are light and the coco has become kinda dry. I give each plant about 12 cups of water/nutes each watering and receive about a 20 percent runoff to waste. Every fourth/fifth watering I use only water ph'd to 5.9 or real close.
I have experienced burning edges of the leaves progressing to burning the whole leaf and then the leaf dies. Many leaves are still green, but the burning/browning is really bugging me. The room is well ventilated and the 1000 watt HPS is about 18 in to 24 inches from the tops of the plants. 70 to 80 degrees fahrenhite and about 40 to 65 rh.
I have had this problem for a couple of months, starting in veg and continuing to the present. I know I should have done something earlier, but oh well.
Anyway, I read the sticky on ph and I have some questions. The water from my hose reads about 300 ppm and about 7.5 ph. I add my General Hydroponics flora grow, micro, bloom at about half strength which brings the ppm to about 900/1000 and the ph to 6.4. I have also used CalMag at about half strength each watering.
I then ph down to a 5.9, water/nute the plants, and check the runoff which ph's to 5.2.
Is this good? I don't think it is. If it isn't should I ph up to about a 6.6 ph after adding the nutes? Would this bring the ph of the runoff to 5.9?
The PH STICKY indicates that soilless ph should be 6.4. Is that the ph of the water/nutes that goes into the pot, or should that be the ph of the runoff?
I am also looking for the acceptable range limits of the ph of the water/nutes going into the pots, as well as the acceptable range limits of the ph of the runoff.
thank you, issac