Originally Posted by Boredomb
On my Ehiem classic canister if you reverse the hose right it won't circulate. This could cause a mini cycle depending on how long it ran like that due to lack of fresh water/oxygen to the bacteria.
"If you reverse the hose right", that's sort of humorous that getting it wrong right might do something different than just getting it wrong. I don't mean anything by that comment other then it rang as an odd turn of phrase. What makes it do that?
The bacteria/archaea have been proven to be very hardy and will go dormant, they don't kill off that easily so a mini cycle will only be an off balance while they process an excess of ammonia. Ammonia over 1ppm can inhibit the nitrite oxidizers which leads to a nitrite spike as they don't get started until the ammonia drops.
Treating with prime and changing water daily after the large water change that Byron recommended will serve to detox the ammonia and nitrites.