I built my very own hang-on skimmer and all seems to be well in the fact that it does hold water. As for its effectiveness at removing waste I can’t say. It is built out of PVC with a Maxi Jet 1200 Venturi style injection device. Every time I open the air valve to start the flow of air I immediately get bubbles out the exit into the tank and my tank become a bubble infested. I am working on posting a drawing or picture. Any help is greatly appreciated. Thanks.