How did you cycle the tank?
What size is the tank and what fish are in it?
I just ask because I'm worried whether or not the tank is "properly" cycled. If you followed the advice from this forum then great. If you followed the advice from your fish store or tanks instructions then it most likely wont be cycled.
Not sure if I remember it right but I think its a 54L with a betta in it that teddybear's mate runs for him and we don't have feedback on whether anything more than fish and tap water was done...
Keep an eye on the neons, mate. They don't tend to do at ALL well in new tanks. You'd be better off returning them and getting something hardier (platys, danios, black neon tetra, harlequin rasboras are all good).
Did you cycle with ammonia then? Or use another method? Interested to hear how it went.