have you seen this?

http://www.advancednutrients.com/nutcalc3public/

i've used there organic line. (iguana juice) and i feed with every watering (twicw a week) without any overfeeding problems. i don't use synthetics so i have no idea about the other advanced products that's why i posted there feeding chart. you just plug in your res. size, add a week to the schedule, pic the product line you are using and it does the rest! good luck