If you are using the yeast fermenting method to make your Co2, your culprit
most likely is room temperature.

I had this same problem until last night.

Because the onset of winter, I keep my house at about 70 degrees. This
dramatically lowered the yeast output to only a bubble every 20 seconds or
so.

I bought a cheap plastic container and a cheap aquarium heater to put in the
container, and then placed the bottle in the container. Filled the
container with water and the heater will help to keep your yeast warm by
warming the water around it.

Today was the first time I used it, and I was amazed at the difference. I
am now getting a bubble over 2-5 seconds now.

Brian S.

"Dave M. Picklyk" wrote in message
news:Y8Ukd.142452$df2.5@edtnps89...
I usually get about 25-30ppm of CO2. After a while I didn't bother to
check
since the plants were flourishing and everything was great. However, in
the
last month I've been noticing algae that I've never had before, namely the
green spot algae on some of the leaves and some strings of staghorn. I
checked the CO2 last week and was surprised to see only 19ppm. I usually
change the bottle every week after a water change (on Sundays). So today I
check it again this week and it's even lower!!---12ppm! What the hell is
going on?

I have an airline that is feeding the bubbles directly into my intake on
my
aquaclear filter with a diffuser on the end. The fine stream of bubbles
seem
to be pouring out like crazy just like when I had a higher concentration
of
CO2...so there's no leak or anything---I'm getting a huge amount of bubble
action.

I did buy a different brand of yeast last month...and that's the only
thing
that has changed. But why would that make a difference if I'm getting the
same amount of bubble activity?

Thanx for any help you can suggest,

Dave.