It should be firmer than typical jelly, you should be able to pick it up without it bouncing around, or anything squishing of falling apart. If it is soft like jello, you probably used too much water, or didn't get it hot enough. it should almost bounce. If the water wasn't near boiling, you can just reheat it and try again since the gel is "thermo reversible"
I might have not heated the water hot enough. It was like a soft jello and not as firm. Anyway, I froze the batch and it works fine. My fish and shrimp love it!