For those of you who use Hornwort in your ponds, do you find it necessary to
replenish them every season?

I live in s. Florida (Zone 10) and find it necessary to replace the Hornwort
in my 7x9 pond quite frequently.

Frequenty as in during the season? If so the fish may be eating it. I have
koi in a fishtank (growing for pond transplant this spring) and they chew
the hornwort when hungry.