DIY CO2 problems

[rekoyu]

So I made a DIY co2 system for my 30g planted Betta tank. Every thing was fine till today I notice there are little particles floating. There are alot of them like dust, when I touch water they just spread open. Its like oil or some thing.
I have only added 2cups of sugar, half teaspoon of yeast in a 1.5L CocaCola bottle, filled the water till the shoulder of the bottle. I have set 2 bubbles per sec and I'm sure the yeast did not mix with the water.
My Betta looks okay, but I'm abit worried about them. Is this normal for a DIY co2 system?

PS: I dont have pictures, I'll post as soon as I get them.

[Time-Out]

They could just be dust. A lot of particles will spread away from the touch of a finger (it's a party trick that, for some reason, I can never pull off lol). Try whipping a fine net around the surface to pick them up.