If its a small tank, like less that 5 gallons, you might have a bubble problem. I always did, but thats because I had a bubble wand. I'm going to grab a stone next time I see one for a good deal
You didn't mention what you are treating your fish for, but I don't know of any situation where a little extra oxygen will hurt them.
If they have a bacterial infection of some kind, the extra aeration will also create an environment that makes it more difficult for the harmful bacteria to reproduce since they thrive in still water with a low oxygen content.