switching filters

[colinman.77]

Sorry for the repost. This isn't getting any attention in the newbie forum...

I'm converting from a sponge filter to a aqua clear for my 20 gallon tank. The sponge filter is cycled, but I don't think it filters the water enough.
My question is, how long do I need to run both of the filters so that the AC can be colonized by the bacteria living on my sponge?

 

[bdobosz]

I would assume you woulud need to test the water frequently to determine that.

 

[Holly9937]

well, if both filters are running, the tests will just show that the tank is still cycled, which it should be! I would say at least 2 weeks, it might not take that long, but I would rather be safe than sorry. I have had several filters running on a large tank that I am still in the process of changing media on occasionally, and been doing so for about a month. Depends on how cautious you want to be!!

 

[colinman.77]

Cool, thanks.
I changed the substrate from gravel to sand so that I can get some shell dweller cichlids. Do you think this would impact the tank's cycle?