It depends if you are drawing the air in before or after the impeller.
If you are pulling air in before the impeller, and then chopping the air, their is the potential for microbubbles so small that they can be detrimental to livestock.
However, air bubbles in general are only an issue for viewing pleasure.
My surge tank cycles about every 90 seconds and fills my tank with air bubbles. No adverse effects have been noted.
However, to enjoy the clarity of the tank, and for photographs, the surge needs to be shut off.
Dave B