Tunze 9002 Skimmer problem

So I just bought one of these second hand and am having an issue setting it up. Once I put it in the tank, at the correct water line, I have to open up the valve fully to get the bubbles reaching the bottom of the cup. The pipe, from what I know is not crinkled. I've tried my best, and even tried another air pipe numerous times to see if it was because of a loss of air circulation, but that doesn't seem to do it. It's also very noisy. If I try turning the valve down, the bubbles just go way down. I've also tried the infamous Tunze mod, but that made it worse if anything. Same noise and less bubbles. I thought it also may have been because of the lack of water in the mini-sump at the back, so I tried putting it in my display tank but there was still no difference. Any help would be appreciated. Video below.

That's probably because the valve is fully open. When I start to close it, the noise starts to ease away, but when I do this, the flow of the bubbles also goes down. I can't have it both ways, and even when it's the noisy way, it's still not functioning correctly. In a bit of a pickle here.