That a lots of bubbles but excel won't create bubbles. Something in your tank did that. Are you using HOB? Is your Outflow splashing into rocks or DW? Observe the tank. Done 30-50% weekly water change?
I do a 20% water change weekly.
I recently actually did a 60-70% water change. Same thing with the bubbles.
I do have a Hang on Back filter, came with the tank (6 gal fluval).
I noticed that there are also bubbles on the moss tree. Always were a couple, but they seem to really be stacking up now.
Should I turn the filter down?