I recently had an epidemic of columanris (it's gone now, thank god!) and I was wondering if anyone has a good, reliable treatment for it? The only reason the epidemic stopped in my tank was the green algae water caused by a grow light that was severely draining the oxygen from the water (which is quite hard on the fish)
On another note, I am never buying fish from Petsmart again! (or at the very least, I'm going to set up a quarantine tank)
High level salinity (salt) has been known to kill Columnaris. If there are no fish, you could try dosing a bunch as an alternative to bleaching. I'd personally still bleach though just to be on the safe side.