the small leaves yellowing at the bottom of your plant is a sign it requires more nitrogen then you are supplying and time to start a 1/4 strength dosage of nutrients if you have not begun to already. your leaf damage appears to either be a deficiency or a nutrient lock out due to pH. you want pH 5.8 for hydroponic and soiless (peat moss and coco coir) and pH 6.5 for soil.
Hi KingJohnC, thanks for all the great pics, links and info.
I thought it was a Magnesium deficiency. I had the same problem briefly when it was younger and the nutes cleared it up. Now it came back more wide spread. I did give it epsom salt, and it seemed to like that for a bit. I'm not quite sure yet. The already damaged leaves are getting worse, as I suspected they would. I'm trying to keep an eye on the new growth to see if it's healthy.
I think my PH is in the normal range, but when I tested the run off before the epsom salts, it did seem slightly high. It doesn't need water yet, so I'm not sure what I should do yet.
Do you think I should give it more epsom salt at next watering? should I mix in some nutes? Maybe I can naturally lower the PH a bit as well.
Thanks again for the help.
Happy Tokerday CronicHempster!