New problem! My tank has been running almost 24 hours. It is completely leak free and up to 79 degrees. The returns have an elbow right before the loc line nozzles that has a hole drilled. The hole is at a 45 degree angle in the bend and is meant for a siphon break. well after hours of tinkering today trying to find the source for micro bubbles I discovered the source was that hole. The right side is doing it constantly(really badly) and the left side does a small burst about ever 5 minutes. Both return nozzles are fully submerged, but they also have check valves right after the union joint. I'm planning to turn off 1 pump and silicone the hole on that return and then let it cure for 24 hours. Then repeat with the other pipe. Will this cause any ill effects? Can I truly trust the check valves? Is there another solution? Other than this my tank is functioning perfectly. Any advise guys?