Mid to top yellowing

might need a little more N... it looks fairly isolated to a few leaves vs spreading all over in a wave. I wouldn't overreact to it. in first pic leaf below yellow one is showing something more than N-def. but still limited and not spreading wildly. it's tough to avoid minor imperfections with that slow release stuff and water-in like gaia green. maybe concentrations don't perfectly spread out? but the ease and convenience can easily outweigh any small issue. any type of estimates of ppm or concentration of resulting nutrients from labels? while ppm may not relate, the amount of grams added of available N can be calculated and compared to ppm-to-molarity-to-grams of a hydro mix and have a good idea if it truly is low or locked out etc.