What is this?

says you went from lockout/pH issues then dumped a whole shit ton of water through it... probably a combo of overwatering along with the fact lockout/pH issues don't resolve overnight even when you have fixed the resting EC of substrate or rez etc (same basic concept). Looks like Ca is having an issue, but more likely from the previous lockout issues you mention in weekly comment so, when you ahve a problem don't dump 10 gallongs through it. If severe, just give plain water with a good amount of runoff. this alone will significantly drop EC. Stop buying flushing agents.. they are retarded and usless. water alone is enough to drop EC. If not severe, simply give what you beleive is a reduced concentration that will average out to a normal level.... make sure there's runoff. This is easier if you know previous levels fed. this is more difficult in a soil context to know with any precision, but can be an option when the problems are small and slow moving -- indicating things are not far off. also, is this just a few isolated leaves at bottom? if so it'll probably not get worse as long as you don't run 10gallons of water through it in 1 day. ontop of lockout from before now you have a dysfunctional root zone until it can recover with very low o2 levels from drowned roots.