Another thought… Most growers secretly and silently worry every day about low air (low O2) problems and power outage, bubblers stop-up, air pumps fail to pump air, water chillers fail to chill, waiting and hoping that nothing like this ever happens. Few growers will ever fess-up to these secret worries.
You do know that you can always test your res water DO Saturation any time and accurately diagnose just how bad a low air (low O2) problem really is or if that is not your problem. A simple rater quality test can rule-out a low air (O2) problem or rule-in this problem and then you fix it if like.
A little DO strip (like a pH test strip) is relatively cheap ($0.50 a test), the little test is not rocket science, it's simple to do, quick and easy. Why keep wondering, guessing and hoping? You might consider spending ½ dollar and see if you really have this problem or not.