Ah, I mistakenly blamed the nitrogen. That was my first guess because it most often effects the lower leaves first and always from the tips/edges in. It is more likely though that phosphorous is your issue. The fert you're using has really high P and K values. An abundance of phosphorous can hinder the uptake of zinc, potassium, and iron.

I'd recommend doing a soil flush and then going a couple of days on just water. I'm thinking that after the excess nutes have been flushed your plants will start to turn around. Wouldn't advise going back to the Chempak either. The N value in the Miracle Gro is higher than you want for a young plant, but perhaps you could dilute the solution to exchanging one excess for another? I wasn't able to find the NPK of Eazifeed.