Is the display tank that the HOB
filter came from a cycled, working tank? I mean... are there fish in it? If so, then the HOB
probably had bacteria built up on it and your quarantine tank *may* be cycled because of it.
But if the HOB
is from a barren tank that doesn't have anything to build up a bacteria population, then your HOB
probably didn't have much, if any, bacteria and isn't going to speed along cycling your quarantine tank. Remember... the bacteria is on the filter sponge, not in the water.
I found it can take a good week or so to get ammonia readings. I wouldn't assume your quarantine tank is cycled until you start seeing nitrates show up with no ammonia present.