I take a q-tip and pull off some extra cotton, then twist it to make a nice pointy tip and clean out my holes. If you take the coil head out you can actually see the a-tip come through the hole. You'll be surprised by the gunk on the q-tip. You can do the same thing to clean out the bottom underneath where the coil sits. If it's gunky the air flow will definitely decrease. I usually do this every other day or so while changing/or filling my tank. It takes about 2 minutes and keeps it clean as a whistle.