Did you post earlier how you made your DIY root tabs? I would love to know how to do it and get some good growth on my swords!
All I did was buy some red clay from Michaels and mixed in Osmocote plus with it. Then pulled off little chunks and dried them out for a few days.
Think I read here in an old thread that red clay would have iron or something in it. Get the air drying type and obviously non-toxic.
If you make them.. they're MESSY if you accidentally pull one up. The clay gets all in the water. Same with putting them in the substrate too. You have to be quick and make sure they get pushed far enough down so the clay doesn't seep in to the water.
Or if you don't want to do that, a lot of folks get empty gel caps and put the osmocote in to those to plant.
Or also you could take some tank water, mix in the osmocote and freeze to make little ice chunks to put in to the substrate. Obviously this would make the tank cold if you put in a lot, but it would be a cheap way to do it.
I like using the clay b/c it keeps the fert pellets in the substrate. with my 40g, when I was setting it up, I just sprinkled the fert on the substrate and mixed it up and then capped it with more sand. Whenever I disturb the sand though the fert pellets come to the surface. It doesn't bother me at all, but I'm sure that would bother a lot of people. I'm sure that would be a problem for the gel caps or ice cubes.