Here are some facts on air bubblers and they do not cause gas bubble disease:
Some reasons not to have a bubbler.
They are not as efficient as powerheads, water pumps, and/or protein skimmers are at creating water movement in an aquarium. All of these are much better at helping with oxygen and other gas exchanges at the water's surface.
· They do not move water fast enough or in adequate volume for what a tank usually needs for good all round, vertical and horizontal, water circulation. This situation can also contribute to a low or insufficient GPH (gallon per hour) tank water turnover time.
· They create a lot of salt spray, that in turn contributes to salt creep problems.
· They clog up.
· They wear out quickly, and usually need replacing often.
· They can give off irregular air flow.
· Air line hoses can get pinched or kinked, which weakens or cuts off the air flow.
· Many times the air pump chosen to run air stones is inadequate, resulting in low air flow pressure.
· Some air flow pressure is lost the longer the distance the air has to travel through the clear tubing from the air pump to the air stones.
· The deeper the tank water, the farther the air has to be pushed downhill to reach the air stones, resulting in loss of air flow pressure.p>
Now to the issue of gas bubble disease:
"Gas bubble disease, like Melissa said, is not due to air bubbles in the water, but actually dissolved gases (both O2 and N2). With many fishes, signs of GBD, will show up when the total dissolved gases exceed 110-130%. With some fishes, O2 levels of over 300% did not produce GBD. Usually, on smaller systems, this is due to the entraining of air on the intake side of a pump. The easiest solution to this is finding and fixing the pump, but having a trickle filter (dembolizing tower), water "fall" into the tank or sump or strong aeration in the tank or the sump will off gas any supersaturated dissolved gases. For this reason, as a protective measure, I have overflow drains, as opposed to siphon/suction tube, and aeration (usually in the sump) on all of my systems. This will also help off gas a build up of CO2 and the associated pH drop that some tanks experience when the lights go off. Also GBD will manifest itself in more than just the eyes, and unless the supersaturation is fixed, it is usually fatal in a very short period of time."
too lazy to put in my own words. HTH!