To be honest though, they do only work for the heavy root feeders. So unless you have some (crypts, swords especially) there's no real use, at least IME.
Thanks again for all the feedback.
Has anyone used these from aquariumplants.com??
We bought some substrate from this guy. And although he was pretty rude to my wife on the phone, his substrate seems to be working pretty well.
rudeness stinks!! but you like your substrate so thats a plus.
i use and recommend the pfertz root tabs. cant hurt to try. i noticed immense growth in all my plants with these. i also use their liquid line.