It is not whether the water will change going over the waterfall, but the
action of the type of bacteria, and the waste products produced. Aerobic
digestion does not produce hydrogen sulfide or methane which smell bad and
are toxic to the fish.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html
"GrannyGrump" wrote in message
news

From Ingrid's post on veggie filters:
"It needs to be only 8-12" deep so it doesnt go anaerobic."

Won't it go back to aerobic if bouncing over the waterfall rocks?