Heavy is over priced and AN is,,,well AN. Screw AN and their salty Urea bullshit.
Dog, the minute you add the "Open" and the "Beastie",,,what are your P&K going to be?
Don't you think THAT will cause some real yellowing???
I don't know what you've been adding as supplements you don't list it.....but it sure looks like it could be to much P&K. Ever flush your media in that hempy? Looks kinda like it could be a lock from salt build up too!
At this point I might TRY some foliar to up that N as the plant is now reducing the uptake of N and stealing it from the leaves.
The addition of more N to the res may or may not work now, unless you flush the build up out.
Those are the 2 things I see it could be....Look at it again with the above info and I think you might be able to answer this one yourself.
Good Luck my friend!
P.S. I really don't see any leaves being "over green". So too much N is not in play.