i understand the folks that use premixed ferts to be ones that dont want to own the responsibilty. if the plants dont grow,(or algae explosion in the most cases) they will complain at the LFS and be persuaded that they need another premixed bottle of magic to solve their problem, normally this ends up with dis-illusionment and the LFS suppling endless variety of plants in plastic form.
not allowing the responsibilty to lay in the hands of the assistant at the shop that has never seen the tank and hasnt even asked what water parameters the tap water has, is the first step to take if anybody wants to have a well planted aquarium.
I have already bought dry fert from plantfertilizer.com and that is the route I am going with. I was just curious about the company. Mixing the dry with RO is easy and I have unlimited RO at the pharmacy. The calculator makes mixing even easier, pretty much a no brainer and a huge money saver. I however, have been reading that the Dry Trace mix is not something you can keep "it goes bad". I am not sure if this is true or not and that is why I was inquiring about the pfertz company and whether I should buy the Trace from them.