He is saying that your Miracle Grow nutes are no good. The general concensus is...don't use Miracle Grow!

For veg you want to go look for somea bit higher in nitrogen, and a bit lower in everything else. When it comes time to flower you'll want something higher in Phosphorus and a bit lower in the rest. Another thing to take into consideration is micronutrients...

If it exists, go find a good fertilizer with high N, lower P and K, and as many micronutrients as you can find. Your best bet would be to probably get some organic fert if you can.

But as far as your yellowing goes, FLUSH your plants with more water than normal and start using your new ferts you get at 1/4 strength.