Wow, thanks for responses! Well mine's a funny kind of bubbler. It's a clam that stays shut until an air bubble (from the air pump ) gets big enough to lift the top lid of the clam. THen it opens and releases a few big bubbles. It shuts and starts over. I guess I need to try it out and see how much it moves the water, but I don't think that it does very much. I used to have it in a community tank with a pleco, and he would get inside of it while it was shut. (It's not a tight shut) So I guess the main concern would be the betta getting caught in it, but it is really slow moving.
Here's basically what it is.