TOPIC: Pool plumbing question

Please see photo. What is this PVC line for and is their a reason it is cut off? Is it some sort of overflow outlet or is it a defect?

Great question. This is where the comment "Recommend the pool equipment be evaluated by a specialist and its operation and maintainence documented"

Anytime I find something that is that different from the norm, I will use that or a similar statement. One has to wonder how that sand type grit got into that tee.

Looks like it was installed incorrectly using black ABS glue instead of purple primer and PVC glue. 

Ding! Ding!  This stuff ain't right, get a licensed plumber in here.

Was the pool running at the time of inspection? Is that a light junction box to the left side?

I can't think of anything that should be wide open like that. Do you have any more pics?

Or maybe its the new style pool drain!!!  Just turn on the pump and watch it drain!!! 

A couple of possibilities:
The system was changed and that part of the plumbing wasn't needed
It may be the end of the drain line vent, if so it should have a screen or cap over the end and be marked.

As for the glue used, it's heavy bodied gray PVC cement not ABS cement. Purple primer is only code for buryied fittings on exposed fitting it's alright to use clear cleaner instead.