Jack's Classic Flood Table PPM Question

I am running Jack's classic 20-20-20 in a Flood and Drain situation. Thanks to the guys in the hydro section they answered one of my main questions. Although I have a PPM question. The directions on the bottle state that if watering everyday, mix 1/4 tsp/gal. So in my 40 gal res that would be 10tsp.

Problem is, that only gets me to about 300ppm. Should I ignore the label and add to my res until I hit the desired ppm?

Thank you ahead of time

Are you sure it's a good idea to use that food hydroponically?

I have heard of some other users having great success with it in hydro. Not saying that it is the perfect nute to be using in this application. Next run I will most likely go with the pro hydro line from JR Peters.