Thanks for the warm welcome! It looks like I'm destined to make every n00b mistake on this trip. Today I gave up and yanked out Lucky's filter, and then Petco went and sold me an Aqua Fern which is, interestingly enough, not an aquatic plant. Well, I'm $2.50 poorer but a good deal wiser now as I consider my next move.
Hopefully my LFS will have some plants for me to buy. I'd rather not pay $39 or so in shipping for $8 in plants. But Lucky is enjoying the aqua fern for now. Hopefully I can get it replaced before it starts to croak.