You have a 5g (20L) tank as a community tank? What is the community made up of; type of fish & how many of each? I personnally would swap the fish/inhabitants rather than the filters if the 10g is sufficient for the stock.
Ahhh, yep that makes much more sense!! Swapping the filters shouldn't be a problem, you may see a slight hiccup in your cycle of the 20g because the filter from the 10g probably won't have sufficient BB for the bio-load of the 20g.Whoops, I meant 20 gallon long