WOW! Just wanted to say that I came across this post again today and I am shocked. I too have been having a problem with yellowing and no growth after purchasing 5 weeks ago the 4 x 8 Agromax Grow Tent WITH WINDOWS! Same dying, yellowing leaves and everything. A buddy of mine also purchased the 4x4 model and is having the same issue! We were back and forth on what it was. Like Nightmare we checked everything, TDS, PH, Temps, Humidity... Tried adding more CalMag, Epsom salts, everything dies or just doesn't grow while more and more leaves just fry. Lights are at top of tent, 4.5 feet away, temps at 82 but STILL THEY DIE! I'm calling HTG and taking this tent down! It is the new one with the windows! I will post a picture of problem but was hoping if any of the above posters might respond if they are having problems with new tents with windows, because I sure am!
Oh and by the way took one of the plants out of tent to mom before switching light cycle and it fully recovered while it's sisters are dying. Oh and I found this post before I ordered it but thought it wasn't the issue because mine is newer model WITH windows. Beware!!!!!! I just want to return this and buy something better, I am beyond frustrated.