curing and ammonia- how high is too high

[MitchM]

You only need about 3 - 4 ppm for nitrifying bacteria to establish itself in a timely fashion.
Anything higher will retard the cycle process and kill off most other organisms.
Ammonia detoxifiers will only last for about 48 hours and with our hobby test kits, you can't tell the difference between NH3 and NH4.