leaf litter and hornwort
Even a few bucephalandra- this largest 'emerald green' one from my tenner
and two small 'green' ones which came loose from their rocks in the main tank.
The ramshorn snails-
All these things brought in enough bacteria on their surfaces, I finally did it. Got an instant cycle. Fed the snails generously (carrot, algae wafer) and tested the water each day. No sign of ammonia or nitrites, small amount nitrate.
Snails showed no signs of distress. They're just cruising around.
A few days later I added salvinia minima (and two more snails) from a package- which created thick surface cover on the left side.
All in all I thought it was a great QT setup that would keep new fish happy for weeks- except they never came. Long story short, I was going to adopt someone's kuhli loaches from a tank teardown, and they never came through. So for now it is just snail and plant quarantine... meh.