Sure lots will be lost, but I see it works pretty well for me.. I use a
soda bottle DIY CO2 into a 35 gal. with about 2wpg and a new 22 gal with
3wpg and there's constant pearling in the 22 gal tank. Note that the 22
gal has a penguin 170 with a bio wheel also and the co2 running into the
intake of the filter. This chops the bubbles up and helps dissolve it
into the water.

I think with such a small tank, any injected CO2 will make a difference.
I'd try a small 20oz soda bottle and run the tube into the input of
the filter. I mean, it's worth a shot, right? If you don't like it,
you're out the cost of a soda, a packet of yeast and some sugar.

Andrey Tarasevich wrote:

Hello

I'm using a Penguin Mini Bio-Wheel on my 5.5 gal tank (one betta, three
pristellas). Recently I added some plants to the tank. Initially I put there
some cryptocorinas and an amazon sword, which seem to be doing very well.
(Amazon sword quickly put out two large "submersed" leaves and more are
coming.) Later I attached a small anubias to a piece of african wood that I
had for a while, and also planted several strands of glossostigma in the
gravel (this one, as I heard, is very demanding and high-maitenance, so I'll
probably end up replacing it with something else later).

Now I'm thinking about trying some DIY CO2 injection, since things seem to
be slowing down (I'm thinking about maybe using that Hagen's Nutrafin bubble
counter with a homemade CO2 source). However, I have some doubts about
whether the whole thing makes any sense as long as I'm using the
aforementioned filter. The filter's outlet is pretty much a waterfall and it
provides some rather intensive surface agitation, which will lead to CO2
escaping from the water. Do you think that it will boil out so much
dissolved CO2 so quickly that the entire injection setup will have no
positive effect on plant growth at all?