I have a 5000 in my 90g tank and it looks fine...not too large at all IMO. I have it running at about 3 bubbles/sec roughly. I'm only getting bubbles coming out of one side of the disk, with a few on the other side, but it doesn't seem to matter as Co2 levels are fine and plants are happy. If it ain't broke, don't fix it. I don't care about having bubbles coming out of every crevice, as long as I get the Co2 levels I need. Once every 2-3 weeks or so, I soak it in a large measuring cup filled with water and a few TBSP's of bleach. I let that soak for maybe an hour, or until it turns white again. That seems to work fine.