Ah you guys are really missing the point... "specific nutrients" ha!
I have been using it for a long time... while I experimented with other nutrient formulas as well and in turn wasting lots of money, his formula won hands down and plants were bigger. Had one with a stalk thicker than my arm at one point (outside).
He helped develop it and perfected in Holland and won the famous Cannabis Cup in Holland as well as being written in magazines well before most of current nutrient companies that are out there. If I remember right it was in the 80's sometime.
I have to agree that comparing to today's specific nutrient formulas out there Cogo's is much stronger and a lot cheaper, I always buy it at his site and never seen the requirement for the card... cogosoriginalcannabisformula is the site
I say if you have a prefered fertilizer, try it against Cogo's on a couple plants and it will tell the story. you can also see his facebook cogo.original he has some amazing movies there... wish I could plant that many