Hello all. I am a newbie at this site. I have a fairly good technical knowledge of pool equipment. But I am stump on my issue and appreciate any help or suggestions. I have a weird union device on my return to spa. See attached. It is the one on the horizontal PVC. I am also having issues on my spa overflow. It seems that the overflow is less than normal. It used to be like a waterfall look. Now it is just a small flow. Here is what I have done so far. Clean my filter. PSI is about 22. Check for blockage and lube all diverters. Check impeller for blockage and lube rings on pump. Check for cracks on pump baskets. I have a feeling that union device has blockage. But I am not sure what it is for. Thanks for your advanced help