..overlooked the really high RH%,.. how high Stoney, like 75+%? This can really start to screw with transpiration rates (read up on vapor pressure deficit, VPD, in the Reference section, nice article there, makes things more clear),... think of the whole vascular system as a giant wick, roots up to leaf tips; water is evaporates out of the stomata opening, while CO2 is taken in,.. this has a drawing effect on both water and nute transport, so if something jams that up, the flow starts to drag more and more, inducing all kinds of potential problems, but odd nute defc.'s are among them! The nutes may be there, but just not getting taken up fast enough, forcing the plant to start scavenging what mobile nutes it has from leaves (mobility refers to the ability of the plant to translocate them from older established tissues to new growth where it's more needed; not all nutes are mobile, some poorly, or not at all; this is a key diagnostic aspect when troubleshooting-- where the trouble is on the plant),... it's like staving to death sitting in a bowl of soup!
All that said, the odd pH drift remains a mystery, and that's a big deal here, RH% aside,....
.. water is nice! Again, how much run-off is he doing when he feeds? Is this guy coco savvy, know all the do's and don't's? ....gear in good working order?
... yellowing from bottom up, top down, mid level,..? Again, no pics makes this iffy,....
... that brick coco, does it need specific preparation solutions, or do they say its good to go after hydration?
.... they say r-o ppm's shouldn't be more than about 250ppm higher than going in,... given the frequency of feeding (usually), lower EC is better,.. most don't feed more than 1.1- 1.7 EC depending on a variety of factors,... same guru notes 5.8 pH better during veg, 6.0 in later stages seems to do best,...
