Do you spray anything on your plants and is that happening all over?
Looks a lot like water damage more than a deficiency.
Media? Nutes? Water? Lighting?
I found a great spot to download FREE POT BOOKS . I downloaded a grow bible first and got lots more. Books look great and complete like the real ones I have here. No web site but just a page of links. Just right click on what you want and then "Save Link As" to download so they don't open first as many are 50+ megs. They got lots. Enjoy.
Miracle Grow is not a well balanced nutrient to feed your pot plants in a soilless or hydro media. They are made to supplement plants, mainly flowers that will not be consumed, that are growing in real dirt that has a lot of the minerals and other things to help plants stay healthy.
Could be your nutes causing your issues and a 3-part hydro nute would be a much better option. You can get a litre each of AN 3-part for under $50 then don't have to worry about pH either while giving the plants all they need to grow well. I bought gallon jugs of all three for $124Can so around $10/L and that was at a hydro store. Cheaper even online unless you have to pay big for shipping.