I am getting some brazilian pennywort as a background plant for my tetra and shrimp tank. problem is, it comes as just a stem. how do I plant it? I have all the other requirements, but really want to plant it, not leave it free floating. I heard that you can weigh it down with really fine substrate, but mine is REALLY clumpy. It just naturally formed into perfect tiny spheres! my shrimp have been caught picking them up! (cherry shrimp, very small) so how else can I anchor my pennywort into the ground? I have bits of heavy gravel, but those are just for looks and even more clumpy. Any ideas?