I don't think I can bear to spend money just to speed up the process slightly. The only HOB filter I have now is a tiny 180L/H one that can fit practically 20 ceramic rings so I won't use it. Other than that, I don't have any more spare equipment lying around.
I tried my best to make the air bubbles rise as efficiently as possible.
What do you think of this set-up?
hello; I am from the time when all we had were air operated filters. I started in 1959. The setup pictured will have some beneficial bacteria (bb) colonies growing on the media. The bubbler (air stone) is not going to have the flow of an impeller but will generate flow.
My take is that there are likely trade offs with gentle flow and with high flow and that the end results can be similar. With the gentle flow as pictured the ammonia loaded water will have more time to interact with the bb as it pass by the bb loaded surfaces. In a powered filter the water moves by much faster with less time for interaction but cycles back much sooner. With the same bioload (stocking density) the end result seems likely to be similar numbers of the bb.
The population of bb is constantly adjusting with regard to its food, ammonia. If The ammonia levels go up then the bb population will increase soon. The brief time lag is sometimes call an ammonia spike or mini-cycle I think. The magnitude of the spike should be determined by how big the sudden increase in the amount of ammonia is. Such as adding a big fish or a lot of small fish.
I ran tanks with no filtration at all (walstad method they now tell me) and with only airstones. In both cases there were bb colonies on the surfaces. The issue being that in such tanks it was easy to overstock with fish. Air powered filters and later impeller powered filters allows us to increase the stocking densities in the same size tanks up to a point.
I think your set up is fine for the intended purpose of keeping some bb colonies active.
Good luck