fish parasites on neon tetra

Question
I have an 8 gallon biorb tank, with only one neon tetra left. I had ten, but now they have all died from little white spots, which I read were external parasites. I treated with a water medication;Mardel, twice, the survivor looks good and it has been one week since everyone else died. I will change the filter and 1/3 the water today.  Will I be able to add more tetra? How long do I wait to add more fish? Should I wash the ceramic media for the biorb? I would like to be sure the parasites are gone.  Help!! katia.

Answer
If the parasites are no long present on the fish he should be fine.  I would wait for about 2 weeks before adding any additional fish to make sure the parasites are infact all gone.  The ceramic media is use to house beneficial bacteria,  do not rinse it or scrub it off or you will remove it.  You can rinse the filter medium and add carbon to filter out the medication along with water changes.