Hey guys. I made a DIY filter today. A large one as extra filtration in my Oscar tank, and a smaller one as extra filtration in my community tank. The Oscar tank filter is made in an old protein powder jar with opaque white sides, so I can't see if it's working properly, but the smaller one seems to have some problems. I have the air stone in, the biological filter in, and it's installed. But the air isn't running through freely. Instead there is a quite large air pocket at the top, and the water isn't flowing through and out. This is my first DIY filter, so I was wondering if I did something wrong. Any thoughts?
