Jon, I have tried the Bubble tubes - got a bag for a field test. The effect seems VERY close to simple Alka-Selzer, possibly lasted a bit longer. I haven't noticed a great difference in my LM catch rates with the Alka-Selzer (if they're not hitting on tubes, they seem unaffected by the addition of the fizz-fizz; if they ARE hot on tubes, they seem to hit them either way). BUT, I have had very good results with PopRocks on smallmouth in some local creeks! Not sure if our PopRocks are what quintebasser calls "crackle", but around here (PA) I have found it to drive the SM crazy! I take about 4-5 "rocks", stick them in the nose of the tube, and plug the tube with a small piece of cotton dipped in some Bang (crawfish scent). I did this one day when we couldn't get bit on anything. It was as if we were fishing a different creek. Rocks will last about 5-10 minutes before needing to be replaced. Bag of PopRocks costs a few cents.