Why are you over 2 weeks into flower and still using half grow nutrients?
Also, you're trying to say that your plants grow to 3 feet in 21 days?
That's 36 inches in 21 days. Lets even say your clones start at 6, thats still 30 inches in 21 days. Seems a little fast.
Judging growth rates by how tall they get isnt the best standard of measurement. Try instead by measuring node development. How many nodes your plant will develop over a time frame...
Reminds me of a neighbor in college bragging about how fast his plants vegged. I went over there and saw he had like 8" internode length.
Just thought that was weird..
And to address the people arguing about strength of concentration in Drnygrow vs AN... Just get 2 bottles of water, 1liter in each.
Add 2 TBSP of nutes and see which one has a higher ppm. Arguing over a thread isnt going to answer your questions, and no one can learn from this.