[bnumair]

Originally Posted by mlott132

At what point should I replace the bio wheel in the filter?

remember the wheel and filer cartridge are the two places where ur good bacteria is colonizing. with that being said if u remove any of those or replace any of those with a new one ur tank will go through a mini cycle.
i never change the wheel itself unless there is something wrong with it. i replace the cartridge every now and then when its very dirty and start clogging.
but here is the way i do it.
for such situation i recommend that u get an extra bio wheel and filter and place then in the tank for 2 weeks prior to changing ur originals. this way there will be enough bacteria on the new filter and bio wheel.
also i recommend changing only 1 item at a time leaving at least 1 week in between both changes.
example: buy new filter and bio wheel place then in QT for 2 weeks.
3rd week change just the wheel only
4th week change the filter.
depeding on the bio load in QT filters may need to be changed anywhere from 3 to 8 weeks.