Thanks for the awesome info! I'm looking to lower my nitrates. Since restarting my 150G last month, my nitrates are through the roof right now, about 180ppm!!! That's even after doing a 50G water change!!! And nope, I don't have any livestock and don't plan on it until it gets down to liveable region, like zero. I'm a little confused to the design. The external clear hose is the input on top. On the inside of the cap, what does it connect to? The yellow tubing inside, what does the upper end connect to? I'm assuming that will connect to the upper endcap. What is connected to the output that is drilled to the side of the tube just below the end cap? I'm assuming the end on the bottom is unconnected, as that is the water feed that will push the water up the denitrator. Either gravity feed, or pump feed will drive the clear tube input, right? Sorry if I am being dense, I just want to make sure I understand before I go and make this. Thanks!