Or, continue treating the 55 gal since there might still be something contagious there?
I know what you said last time, and that was the entire tank at this point, so am leaning in that direction, but want to hear you say that’s right. I’m going to change the positioning of the HOB filter and sponge filter to change the direction of the water flow a bit and then add an air stone near the bottom of the tank to increase the oxygen and movement. I used to have one there before this all started to turn sour and took it out as it ticked off the dwarf red Gourami, “Il Duce”, who has been using all his spare time building floating plant islands and building bubble nests, also a great pain in the butt when it came to constantly clearing the slots in the bottom of the filter uptake, but he would have his way.