We might need more info to help
Is the 10 gal cycled? ? Are you moving the Otos to the main tank after quarantine or are you upgrading to a 20 gal? If the 10 gal is cycled just move the filter to the 20 gal along with the new filter (or put the media from the 10 gal's filter into the new filter if it fits) which will keep the 20 cycled for the Otos assuming it's a new uncycled tank.