KD, what brand of coco are you using. All coco's except b'cuzz (i think) and canna coco require a hearty flush before you can plant. They have a lot of salt buildup.

I run in coco and i set my ph to 5.7 and it will sty there for a week or longer. I dont know, but my 15 gal res only needs an adjustment when im filling it. I can leave it and have no worries for a week.

KD, also you cannot let the coco dry as the Ca will get locked up, so make sure it stays damp.

Run some 5.8 ph water thru and see what the runoff is after a hearty flush, also check the EC or the PPM of the runoff.

KD, also i use calmag every time, i add it in the rez, because i use RO water.

SORRY, BUT THE GUY NEEDS HELP...the link is to an established coco forum, and you can find all and more info there.
CoCo