Re: Scratching the surface of biowheels and bioballs

["James Purchase" <jppurchase at rogers_com>]

Scott H. wrote:
"But if the idea is to get as much surface as possible into a volume
while ensuring plenty of air exposure, I can think of lots of things
better than bioballs and wonder why people buy them for use in
biofilters."

Simple answer is that they don't "clog". Probably the most rigorous
information on biofilms in the hobby literature is in Spotte and he speaks
at length about the need for a substrate which will allow older (and less
productive) biofilm to slough off and be replaced by fresh. The surface of a
well designed bioball (I'm thinking of the two sizes made by Dupla) is
practically guaranteed to never get clogged by detritus and the older
biofilm can just wash off easily, presenting a fresh area for bacterial
colonization.

Sintered substrates apparently do "clog" and need periodic manual cleaning
(bleaching) to remove the built up biofilm and this gets less and less
effective until all of the interior spaces are blocked. The info that comes
with Schott granules states that they should be replaced after a period of
use.

James Purchase
Toronto