[ge0rge]

for my bub, i use formula 420 (b/c i got it free with the pipe)... it works awesome. But, it smells a bit afterwards, you can take care of that by just washing out the pipe afterwards with hot water...

I love bub by the way...

EDIT:
One piece of useful info...
If you get a 'bub with a "slider" bowl on it (ie, you can remove the bowl, like a bong), it is sooooooo much easier to clean, fill and empty water from the pipe.