Have you tested the water out of faucet / tap for ammonia?
Are there fish in the tank, or are you fishless cycling?
Did you use the same filter and media from the 10G. Did you change the media /filter pad or wash it with tap water which wasn't treated?
Or did you start fresh with a new filter and media?
Here are some articles which might be of help - since I am not sure if you have fish or not I included both options with fish in the tank, or fishless. Then the general information has many good tips to help keep a good, stable tank.