All of a sudden my Eheim 2217 has started making A LOT of air bubbles out of the spray bar. So many bubbles that my tank looks like a snow globe. At first I thought maybe my CO2 regulator went haywire and was putting out too much CO2. But my CO2 has been off for several hours now and the air bubbles are still coming out of the spray bar. Plus, I hear bubbling sounds and occasional "burps" inside the canister. I guess this means it's sucking air somewhere, right? How do I locate and fix the leak?