Hm, this is odd. I've seen it before (don't ask how long my fishless cycle took lol) but I've never figured the cause.
I do have one question (well maybe two lol):
1) Did you use dechlorinator when you filled the tank? If so what kind? (sorry if you mentioned this before)
2) What are you using to dose ammonia? Is it accurate? It might be the photo but the green in the photo looks darker than what i remember 4 to be on the API Kit but again it might just be the light in the photo. Overdosing ammonia can cause a stall as well.
I have two suggestions:
A) Do a 100% water change (use dechlorinator of course), wait an hour and then test ammonia (make sure you shake both bottles for a few seconds and then wait 5 minutes for the results). If you still have ammonia then you may have overdosed. If you don't, then only dose to 2 instead of 4.
OR
B) You mentioned this is going to be an upgrade to a 10 gal? What's in the 10 gal now? What you could do is move everything over from the 10 gal (fish, filter or filter media) and anything else you want to this tank. If the 10 gal is cycled and you move the media over the larger tank should then be cycled as well (monitor levels for a week or so just to be safe though). Just remembver if you add new fish, do it slowly and only once you're sure levels are stable because adding more fish is going to add to the bacteria load and they'll need time to adjust.
I also saw your stocking post a few pages back but I'd like to know what from the 10 is going into this tank before I suggest anything else.
Whether you do A or B is up to you. Let us know what happens
