DIY CO2 problem

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.

 

it is just pulling charged particles out of the water... similar to the way a protein skimmer works.
It is like a concentrated layer of dissolved dirt in your tank. just scoop it out and it will eventually go away

 

The same thing happened to me when I had a planted tank I would just take a cup and use it to skim the water a little bit. Ideally you could get one of those surface skimming attachments for your filter. I think eheim makes them. i never bothered getting one just surface skimmed everyone in a while.

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