You may not need to go to "zero" white spots, but just ensure there are only a few still visible. Some of the later white spots may be "scars" and not viable trophonts, so waiting for those to go away is counterproductive.Makes sense. Once fish show zero white dots, THEN start counting 30 days.
question - my 10g quarantine sits right next to my display. Should I move it to another room? I was reading that ich can be airborne.
Nearness of a QT to a DT is a known issue. The worst case is seen at some LFS where they have infected tanks above others, and water drips, causing contamination. Simply close proximity can also result in the aquarist making a mistake - dipping their hand in the QT to feed, and then moving on to the DT.
Aerosolization is a more or less theoretical mode of biosecurity failure where a disease propagule is entrapped in a tiny water droplet that moves into the air above an aquarium, drifts in air currents, and then settles in a new aquarium. Due to the small size of these droplets, it would be presumed that mostly bacterial or viral diseases could be transmitted in this fashion. Tank covers and tank separation would be two means to limit this mode of transmission. It has been reported in the literature (citation unavailable) that Amyloodinium spores can travel 12 feet inside aerosolized droplets of water and Aeromonas bacteria can travel over 20 feet. However, propagule pressure also plays into this – it can take a number of pathogens entering a system to actually cause an infection. In most instances, separating aquariums by about six feet, and never stacking aquariums (with potential disease issues above) removes most of this risk.
Jay