sweet i found on the 4hydroponics.com...
Hydroponics rock wool or NFT systems:
Small or slow growing plants = 1 to 2 teaspoons per gallon
Medium sized plants (most applications) = 2 to 2½ teaspoons per gallon
Large or aggressive vegetative plants = 3 to 5 teaspoons per gallon
Do not exceed 5 teaspoons per gallon of solution. If plants show signs of stress, reduce the amount of nutrient in the solution.
Safe to use in conjunction with other nutrients. Age Old Organics Bloom and Age Old Organics Grow are very concentrated products - measure accurately and remember to keep the pH of the nutrient solution between 5.8 and never above 6.5. If possible also monitor the solution with an E.C. meter, keeping the solution in a range of 2 to 4 mill/Mhos/cm.
Soil applications:
For vegetables, flowers, and tropicals, add 1 to 2 Tablespoon to one gallon of water. Apply directly to leaves three weeks prior to bloom and then every 2 to 3 weeks.