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Not sure if you can have too much oxygen in the water, but never heard of something like this. If you want less bubbles put a valve on the line, one usually comes with a pump or get an air control kit for a couple bucks from your LFS.
I think its up to you how you'd like it to look.
The two bubble bars I have at the back of my 60 gallon are VERY much more aggressive in output than what you have there; I don't seem to be having any issues with my goldfish and the extreme oxygenation. My pump allows me to dial back the amount of pressure being fed to the bars...does yours have such a device?