Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Looks like it is a slow release fertilizer, perhaps similar to Osmocote. I think I would try half or 1/4 as much, those instructions are for land plants.
On land the water is intermittent, so the fertilizer is releases slowly, when you water the plants.
In the aquarium there is always water, so the ingredients are always leaking out of the pellets. It can get to be too much fertilizer, especially if you have a more open sort of substrate like sand or gravel.
Test a bit, maybe put a dozen or so granules under the substrate and test the NO3 after a few days. Use the ice cube method or just poke them in deep by hand.