I started out on my little 3 gallon trying out a variety of diffusers and
after about 5 or 6 different ones over a couple of weeks finally decided
that the Rena 2" diffuser is the best at producing a fine mist of bubbles
over an extended period. Note that only a few pores in the diffuser ever
emit CO2 at any one time. I typically got about 30ppm as long as my CO2
bottle was perking along. Note that in a 3 gallon the bubble stream only has
about 8" before hitting the water surface. A larger tank with a deeper water
column would likely find the CO2 dissolving more completely before it
surfaced. BTW, if you do use the Rena be aware that the rubber caps on
either end can snag the mist as it rises and aggregate the bubbles into
larger ones which will reduce its effectiveness somewhat. I trim the rim off
the upper end to prevent this.

I didn't like the look of a 2" bright white thing in the little aquarium
however. It could be seen even when I stuck it behind the pickup tube if I
moved a little to one side or the other. And in a 3 gallon everything sticks
out if it isn't right. So I decided to try getting rid of the diffuser
altogether and just input the bubbles to the intake of my filter tube as you
have. My CO2 level dropped to about 20ppm which was OK but not great. The
whoosh might drive some folks crazy but I didn't mind since it gave me a
constant reminder of whether the CO2 bottle was working or not.

Lately I've begun revisiting the Rena but trying the ceramic cylinder cut
down to 1/2" length with a dremel cutoff tool. Since it only emits from a
couple of pores anyway why have it longer than necessary to attach the input
and bottom stopper? I'm now back to 30ppm which I like better now that I've
got some other nutrients in better balance. I've got it hiding again behind
the pickup tube and it's less conspicuous than before but not perfect. I've
got a little leak from the bottom which isn't really a big deal but it's
spurring me to remove the end plug assembly altogether and just dip the end
in RTV and let it cure. If I do that I can reduce the length by half again
to 1/4". I know, I know, I'm obsessed! ;-)

My next tweak will be to try to dye the ceramic. I've got some dark brown
Rit dye which might dull the whiteness enough make it a don't care. If that
doesn't work I might just use wax crayons to color 270 degrees of the
cylinder with a camoflage pattern and let the CO2 emission come from the
remaining 90 degrees which is toward the back of the tank.

Obviously I have too much time on my hands...

have fun!

jtm

--
Remove NOSPAM for email replies