Sounds like it's time for you to get a decent reactor. I have one jug
of DIY on a 20g going into the Nutrafin bubble ladder and get 15-20ppm
with one bubble every 3 sec. Not even all of it is diffused. I know
we are not quantifying things very well here. Your small bubbles may
be half the size of mine. But its definitely something to think
about.

James