Yellow Leaves using LST

I have been playing around with lst and as you can notice from the pic some of the leaves are very light green/yellowish color. All these leaves are between the outer ring of leaves and the inner cluster of leaves. Now if I had to guess the leaves that are becoming the new colas are taking all the nutes for growth while depriving the middle leaves which due to bending have become the bottom. Also if I had tt guess some more N would make them m uch greener. But is it really worth it? I dont want to give to much N and possibly fry the tops. I have been adding 2.5ml of Envy Part A every 3 days with my PPM at 890. Which I know is low but I had some nute burn issues early on and have been taking it slow on building them back up. The Envy is 7-0-5 so its strong on N. Like I said Im just a little concerned and looking for some opinions. Thanks

i have expierince with soil and just started to dabble with aero, looks easy enough as N, you said you give 2.5ML/Gal...what does the lable recommend? usually people start at 1/4strength and work its way up....2.5ML is 1/2 a teaspoon so if your lable says a TSP/gal maybe you should bump it up, also all my ladies are harcore LST'd and you know what, all my older leaves get yellow, but very slowly, i think between your grow and mine theres a legit point, the plant focusing its energy on the new growth, especially since in its traditianl manor new growyj occurs later when we actually expect some yellowing, perhaps upping the PPMs would help you out, that baby needs N and is using it up fast, how long have you had her at 890ppm? as far as i see it, its straight N, your foliage looks nice and clean and she looks real nice, another question, how long has she been in your system? have you flushed yet?