The pinhole pattern of necroses on the tip of the leaf in the bottom-right (which I assume to be older growth) is characteristic of potassium deficiency: K is remobilised from mature growth in order to furnish newer growth.
But this could well be a red herring: necroses in older growth that are the result of potassium deficiency may be induced by other factors, such as excess nitrate and sodium (Ashley, Grant and Gabov, 2005). Likewise, inadequate nitrate can also inhibit K concentration in the substrate, which is more of an issue for lower layers of older (sometimes newer) growth that receives less water circulation (YanaI et al., 1996).
Because Easy Green is very low in nitrates and phosphates, it might be an issue in that respect. Your suggestion of upping the dose to two times a week sounds good. Likewise Joceyln's recommendation of Thrive is excellent as well.
Thrive is best kept in dark bottles, mostly for the iron. When dosing into smaller tanks you would want to use an oral syringe... ie if the nilo dispenses 2ml as dose for 5 gal, just shy of 1ml would be the dose.
A full tank shot would really help in figuring out if it is an actual deficiency or just in need of a trim
I want to switch over to S but my tank is only two gallons. One pump of S treats 5 gallons. It's 500ml bottles, would cutting it 50/50 with in a 1 liter pump bottle be OK? Also, are any ingredients in Thrive photosensitive?