I've just seen the most amazing thing, and I'd like to know if there's a
reason for concern. I have a small recently planted tank (20g). I switched
off the light, and 20 minutes later there are 50 trumpet snails "beelining"
it to the surface along a congested path in the middle of the front glass.
It looked like a highway during rush hour. They were even releasing their
offspring as they went. By the time the adults reached the top, there must
have been 20 young snails mixed in with them. I really wish I owned a
digital camera. All this occured on a path that was no wider than 2 inches
across.

I'm concerned that since I started a Hagen CO2 system today that the water
parameters have changed too drastically. My Ph went from 7.6 to 6.4. I
added the plants 2 days ago, and I know it affected my Ph. When I woke up
yesterday, my clown loaches were poking out the top of the water (apparently
for air). I immediately turned on the light to hopefully start the
photosynthesis process. My loaches used to come out all the time when I had
a cheapo 15W fluorescent. Now, they hide all day with the 55W PC I have
running.

It seems that most people advised not to try to stop the CO2 at night. With
a yeast system, this seems impossible anyways. I was wondering if it would
be beneficial to turn on an air stone from a pump though. That might help.
I definitely didn't enjoy the sight of my clowns bobbing for air come
morning.

Any advice would be appreciated.