I have a 5.5 gallon tank
Ammonia: 0.50 ppm
Nitrites: 1 ppm
Nitrates: 5.0 ppm
(Tank is still undergoing cycling process)
Recently I had noticed a biofilm gathering on the top of my tank, which hadn't bothered me so much until it started getting thicker, and broke into white chunky flakes (it was pretty gross) It was mostly hiding behind the filter pad I use to stifle my AquaClear's flow. Now I noticed it's on the top only, it floats and unless you stirr things up it wont sink to the bottom. It doesn't have a smell.
Unfortunately I dont have a photo because I siphoned out my tank, some of the gravel and even cleaned the top layer of water. Is this normal? What is it? How can I prevent this from forming again? it's pretty gross.