"teri" wrote in message
...

If you move the filter used on the 3g temporarily to the 20g, then the
20g is essentially cycled. The filter contains the waste processing
capability balanced to the requirements of your 2 Platys.
I thought of that but the filter on the eclipse 3 sits atop a frame
in the tank, no way to hang it on the back in another tank.
teri

Alternately, take the aged sponge material out and stuff it into the new
filter. One technique I often use is to take the old filter material and
squeeze it, so the brown gunk falls into the new filter media. I don't
usually mention this method because I've never rigorously checked to see
how well it works, but if you have no recourse.. ymmv.

Any slimy objects (rocks, heater etc) from the 3g will also be coated in
good bacteria.
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