Shags, review your feeds info for us,... what you use, how much, how often...
It's more than one thing I think, looks like underfeeding with this mix of symptoms. I do see some early P defc ( some leaf coloring, start of a bit of necrosis, yellowing); N defc tends to hit lowers first and strongly, not so much an overall color loss... More than one nute being deficient will cause mixed symptoms, harder to pin down,..
pH is always in play, and what medium you use is a big part of that... So is adjusting your input pH's before going in... But knowing what the in-pot pH is matters a great deal, best course of action will hinge off of that. problem is I'm betting you have no means to measure it by, and run-off is not a reliable way to do this... Best tool is a soil pH probe (not the cheapo units, they suck)....
At best, using pure water (which won't skew results like hard water or worse, feed solution), it can show if pH is badly off enough to suggest a corrective action, like flushing.... That has it's share of down sides too, BTW, since you are water logging the soil, and stripping out everything that's soluble! Typically you start with 2-3x the pot volume. This is why you see advise saying to use about 1/4-1/2 strength nute solution in final pour to restore and rebalance the nute load in there....
Flushing needs be done fast so as to not suffocate the roots and kill them... It's wise to have a TDS or EC meter to monitor the run-off for ppm's/EC and check progress, and not just be guessing...
.... "Sativas" tend to be lighter feeders in general, some of the Hazes can be tricky about nutes too. So unless you've been underfeeding, this is more likely a pH issue.... fill in that form for best diagnosis!
.....if you can copy and paste the form below with as much detail as possible we'll be able to give you a far better diagnosis 
