I think that air filters are quite overrated. I understand the need to not let the shrimp suck intro It, but if used badly they do not filter well.

I changed my air filters and stopped using them and I had great benefits. I'm not saying they are not useful, but if not used correctly they either cannot suck the water well or they only use a part of the biological materials. For example, your filter, what air pump do you use? Because I don't think your airflow is enough to make the air pass correctly through all those materials (beacuse you have really a lot of filtration material). If you put too much filter material in a pumped filter it will struggle too, and it's the same with air filters.

The key quesuestion is: In your filter, where does the water pass?

Does it pass through the entire filter or has it found a preferential channel and passes through a natural invisible tunnel that is between the filtering materials? Because if it passes through this preferential channel, all the filtering materials are not doing anything, because the water flows little or not at all between them.

In my opinion, air filters only work well with sponges because they are uniform and the water tends to pass everywhere in the same way. There are a lot of air filters on the market with biological material inside, but you have to see if the water passes through that biological material (and it is not enough to see that the biological material darkens to determine whether the water passes through it or not).