I don't have an airstone in there, I can easily add one
The gravel was soaked & rinsed
the surface looks like it has a skin on it, would be my best description, with bubbles in it, not all in the same place, but dotted around the surface
The filter is new, I rinsed the media before putting it in
Oh and I tested the water today,
ammonia &
nitrite 0
nitrate at 5. Filter media has a piece from my established tank, and added some gravel from there too, my main tank does not have this problem tho so I don't think it transferred