Glycerin works. I use mineral oil from Rite-Aid or Walgreens. It's $4 for a huge bottle that I used to fill up 6 bubble counters. And I still have half the bottle left!
You're not kidding... Came up to about $12 & change w/ shipping.This is the Bubble Counter Liquid that I use. It's a little pricey though.
http://www.marinedepot.com/md_viewItem.asp?idproduct=KL3311
Do you have a pressurized set up??? Thanks.I have never added any water in bubble counter in 4+ years??????