Thanks for the quick reply! It's very possible that the readings were wrong. I do have a few live plants in the tank, but not enough to warrant such a fluctuation in the reading. I will make sure to bang the bottle etc tomorrow (no more energy left for more tests tonight) as I've just been shaking it, so sounds like it could be that being the problem.
I have indeed been dosing ammonia to 4ppm every 24 hours, and it has been reaching 0 by the next day. So from what you say, starving bacteria is out of the question it seems
Phew!
I've yet to test the pH as I was waiting until after the first PWC after the nitrates go off the chart, but obviously now that the readings are abnormal I will test pH too and get back to you with the result tomorrow.
I'm using seeded media from a friend and decorations/gravel from the 5 gal, I was pretty shocked myself to see it go so fast still though! Maybe it's just slowed down after such a speedy kickstart, and like you say the Nitrate test has been innacurate or something. So, pH and crazily banged and shaken Nitrate tests here I come. Thanks again!