Bio wheel is an excellent choice for a quarantine. If it is an observation-only quarantine you can use the standard filter inserts that are the fuzzy white media with activated carbon. If you plan on using any meds or copper, no activated carbon. I like to take the standard filter insert, cut a slit in it and dump out the carbon, rinse it well and then stuff it full of poly-fil polyester pillow batting to get extra surface space for bacteria and a little extra mechanical filtration. The only thing you’re really worried about with only fish in the qt is ammonia, which bacteria will take care of if given enough space to propigate (where the bio wheel/poly-fil comes in.) i dump in a bottle of bacteria and let the filter run a day or two to let the bacteria attach to the media. It’s pretty much ready to go. Then I use an ammonia alert badge which is a little tag that suction cups to the inside of the glass and will tell you if ammonia starts to rise. I find it’ll usually go a couple weeks to a month before the water starts looking dirty, then i do a water change. The only difficult part is you need to make absolutely sure that your new water is pre-dosed to the same amount of copper if you’re using copper. Any drop in copper level below therapeutic range can allow pathogens to hatch and attach to your fish before raising the copper level again. Hope that’s a good starting point, good luck and welcome to R2R!
