I set the pH in the very beginning by using cal-mag. I add 12 mls to 4 gallons of RO or Rain and that's enough hydroxide ion to stabilize the water which will give a 5.5 pH. From then on the pH is pretty much set, even after adding nutrients.
I should not be commenting on this thread because I no nothing about coco coir. My apologies.
I should not be commenting on this thread because I no nothing about coco coir. My apologies.