I'm not a noob but my issue probably seems like one...I recently sent 5 beers to a competition and 2 of the beers had comments about oxidation. I have been brewing for 3 years and have continued to improve much of my process during brew day but have neglected bottling. I was bottling a beer a few days ago and noticed a small layer of very small bubbles on the top of every beer I bottled. I thought this was occuring because I had the flow rate very fast and as the beer entered the bottle, it was getting agitated. To counteract this I closed the spigot some. When I did this I noticed that just under the spigot looked to be a tornado in the tubing, and very small bubbles farther down the tubing just before the bottle filler. I thought air might be coming in from the small hole on the front of the spigot so I covered that but it didn't help. I put a hose clamp on the spigot, but that didn't help either.
First of all, why did there appear to be a tornado in my tubing when I started to close the spigot?
Is there another way to slow the flow rate down rather than closing the spigot?
Any other tips on preventing oxidation during bottling would be greatly appreciated.