My experience with the stock hood on the flex is that you NEED extra airation. There is just not enough gas exchange. When I put an airstone in the tank I saw a NIGHT and DAY difference in the health of the tank. I can't stress this enough. An airstone (as unpopular as they are in modern. Reef tanks) also provides sufficient surface agitation to break up films.Yeah, I think this would be fine for freshwater but they missed the mark for saltwater. Superglue might work if I can’t get the custom made overflow blockers that someone mentioned earlier. Thanks for that idea!
It doesn't have to be horrible or unsightly. I have the stone 2.5 inches below the water line in the back corner just under the return. It does not release microbubbles.
This was an overnight change for my flex. I've never used an airpump in a reef before this, but on the flex it was an absolute game changer.
Give it a try!