Kinda small pictures but first thought it might be mag. but the leaves look really dark which suggest it could be nute burn. Too much nutes. What are you using time release soil or what?
No curling on the tips? Looks like a calcium/magnesium deficiency. The leaves wont bounce back. Are you using Reverse Osmosis water??? If so add 5ml Cal/Mag per gallon of water. Your plant has probably sucked up and absorbed all the nutes that are in Fox Farms Ocean Forest or happy frog they usually only keep the plant happy for about 4 weeks.
Here is a chart, ust try to figure it out by this...it might be a little easier because sometimes it is the texture that is off, and that is hard to show in a pic.
no im using tap water with ph down.. started with lower leaves fading color and curling up and turning bronze with patches. now its on a few top leaves.. i just gave it grow it green very low strenght last water.. and thats been my only time using fertz the whole grow . besides using super plant tonic in the beginning