I have several tanks, and 2 in particular, that both have Tidal 75’s that have the built in skimmers… coincidentally both of these tanks are 45 gallon talls… I typically use at least 1 - 10 inch air bar in each tank, and with how these tanks are easiest set up in my situation, the skimmers end up pulling in some bubbles which end up hitting the impellers in these pumps, splitting the bubbles up into micro bubbles, with the filters sending them deeper into the water… I’m not doing this thinking about better aeration, just a matter of fact, with how the tanks got set up… one tank has a larger Angel Fish, and for whatever reason, it seems to collect these micro bubbles on it’s wide sides, depending on perhaps where it sleeps or ??? But at times it looks like it has Ich, and I watch it pretty closely, and a little later, it looks fine… I think the spots are just micro bubbles stuck to its coat of slime??? If this is the case, is that bad for the fish… if so, I may need to find a way to divert the bubbles, or block the skimmer on those filters???