I havent used one in soooooo long! Do they even commercially make these any more?
A quick search says yes!
https://www.futurepets.com/Pres/VOR0...RoCVi0QAvD_BwE
looks alot like mine.. mine had glass jars though.
Mark,
https://www.futurepets.com/Pres/VOR0...xoCOxcQAvD_BwE
is good for 250 gals for $200
al