what were the measurements you used for each component?
whats the bottle size?
what kind of water did you use, hot/cold/room temp??
check that theres no gas seeping through the hole you made at the caps
for the stone you can use a regular stone but if you want try a wooden, with it you will get a finer mist of bubbles. You can place under your filter or your filters intake.
edit: how long of a tubing did you use?
What level are you keeping the bottle compared to the airstone?
my bottle size is a 2 liter
room temp/cold
no holes
the tubing is about 1 foot
the stone is at equalized level as the cap