I wouldn't glue anything The riser tube has an O ring on it for tightness. That's all I would worry about for now. I have to take my tubing apart when I remove mine from the sump to get it out, so glueing is not an option.
I also removed the B tube on mine, and turned the elbow just that it broke the water surface. That really helped me with micro bubbles and less back pressure. Every one is different so maybe this will help you out