I love hornwort...and it's not  merely because  it is one of the few  aquatic plants that grows exceptionally well for me, although that certainly helps.  I expect...and am rarely disappointed...that it will essentially die off when placed into a new tank or pond, with  shedding needles and disintegrating  stems to deal with for a short time.  But then it always rallies and grows back strong and beautiful.  I just had this occur in the spring when I placed it into every one of my outdoor stock tanks and my inground pond; the stuff  pretty much fell apart, but new growth occurred  immediately and it's done amazingly well all summer.  In a few weeks when I bring a bunch of it back indoors, it will do the same thing:  die off, make a mess, and then come  back with a vengeance.
I've pruned it back several times already this summer, which entails forking out huge handfuls from each pond and composting it.  I no longer use it in my DIY gel food, mainly because I have even more duckweed for that purpose and it blends much more nicely in the food processor.
But it feels  great to carry a bushelful out to the compost heap a  few   times  each summer.  In contrast to my indoor tanks, the ponds  get  very little in the way of water changes.  A bushel of Hornwort on the compost heap translates  to a big helping of nitrates  removed from the system.