Surface Agitation/Gas Exchange

[Samw]

I had a Tunze Nano set up on my 38G years ago and it did not raise the o2 levels enough for my bioload. The reason was because the oxygenated water from the skimmer could not escape the skimmer box fast enough since water exchange is not induced but is through diffusion over 2 pinholes at the bottom of the skimmer.

My Aquaclear provided more oxygen to my tank than the Tunze Nano skimmer.

I did not have o2 problems with any of the other skimmers that I've used (Remora, Urchin, MCE 300). Makes sense since those skimmers have pumps feeding water into the skimmer and thus displacing the oxygenated water back into the tank.

I can't speak on whether the Tunze Nano is sufficient for a lightly stocked 15G tank. It might be.