How many varieties of hornwort are there? I can never seem to find it on the
Tropica site.

I bought some yesterday from PetSmart along with the three new Ottos and it
seems to be a different variety than the pond hornwort I've had before. It
has coarser, shorter needles than the pond hornwort and is much longer.

It's also turning yellow and I can't imagine why. Perhaps it's the water
temperature? It certainly isn't light or nutrients.