Surface agitation vs oxygen

[Randy Holmes-Farley Verified Community Expert]

I’m running my first ever HOB filter for a reef. I changed to an Aquamaxx filter that had a waterfall style overflow instead of the trickle that I had before. I also run a Nero 5 for flow but I can’t get it to the surface as close as I’d like because air bubbles form. My question: how do I know if I have enough surface agitation to prevent my fish from dying due to lack of oxygen?

If they are alive, that works. lol

Seriously, if you are thinking you may have low O2, then look to fish behavior (like breathing heavy near the surface).

It does not take a lot of motion to prevent deaths. It may take more to prevent nightly O2 lows that may stress organisms.