I know in the hobby it is always repeated that bubbles don't aerate, but that is wrong. It isn't just at the water's surface that aeration takes place, it is at all water-air surfaces. The oxygen doesn't know if the surface is at a bubble or the tank's surface, it just knows how to diffuse from high to low concentration. There is a reason bubble aeration is used in sewage treatment, why protein skimmers are considered more than enough aeration on a saltwater system, why you use air stones and not water pumps with K2 type medias, and why professional aquarists at zoos and aquariums use air stones for aeration (it isn't just for looks). Those bubbles produce massive amounts of surface area that expose all that oxygen rich air to water, and constantly new water that isn't already saturated and in addition it definitely doesn't have any film on it to impede oxygen diffusion the way the surface of the tank can have.airstones are debatable on how much O2 they actually provide into the water column. Unless those bubbles that are hitting the surface are either huge or causing a really good surface break, airstones don't do a whole lot.
HOB filters are great for O2 saturation into your tank, another great option is if you are running a sump to either have the drain pipes or the returns above the water line, this will create excellent O2 levels as well. I personally keep my drain lines above the water line in the sump tank and my return below the water level to cut out noise.
People may doubt it and regurgitate the usual 'bubbles don't actually aerate', but repetition doesn't make it any more accurate.
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