I have to fix a misconception I put in here the other day regarding Prazi
staying in the pond unless water changed out. I've since read the
Pondrx.com's Q&A: The Answer:

Prazi will reside in a system at least three days. I can tell you that
because when praziquantel [Droncit] was really expensive, like $7 per pill
from the Vet, you could set up a tank and deworm Discus with it for about
three to four days on the same tank load. Past that, no one thought the
stuff hung around much. So, let's go with three to four days 'residence'
-While it's interesting to note that repeat dosing is not needed for flukes
with Prazi, perhaps because it permeates and stops the developing egg or
embryo like no other medication we have.


~ jan (Do you know where your water quality is?)