I have an All-Glass aquarium with dual MegaFlow overflow systems. I’ve connected both up identically. On one side, the drainpipe seems to be working fine but the level of water in the other one seems far higher. The level reaches almost to the top of the curve in the drainpipe and the flow into the sump is full of air bubbles. It almost seems as if the strainer is blocked and all the flow is through the anti-siphon holes but the strainer and the pipe to the sump is clear.