Duetto DJ-50 as CO2 diffuser?

["conrad harkrader" <c_harkrader at charter_net>]

Heyla,

I've been using a Duetto DJ-50 internal filter as my CO2 
diffuser with a DIY yeast setup.  I changed the bottle 
yesterday, and had lots of problems.  After putting the 
new bottle in, the Duetto started blowing bubbles in its 
output constantly.  I figured mebbe a line had come loose 
somewhere, but I checked them all and they seemed fine.  

I put some more sealant around the two rigid tubes that go 
into my DIY bubble counter, and changed the airline tube 
between the bubble counter and Duetto anyways.  I left it 
for an hour and came back and was still having the same 
issue.  Now I've got the airline intake on the Duetto 
covered and am just bubbling CO2 through an airstone.  Any 
ideas what the problem might be?  Thanks!

Rich;)