1. I have 2" TPRs. Before on the back of the flange there's a hump for each screw. Should the flange (not the outer ring) be inset in the block so it's flush with the wall or can it sit against the wall. I drilled holes for the screw nubs so it sits flush on the wall but before I set it permanently I thought it might be better to inset it so it's flush. Opinions? I'll be adding a liner and underlayment.
2. I going through the wall with a 2" pvc. Would it be better to run solid PVC all the way back to the filtration or would flex pipe work? Maybe 30 feet on the longest run and flex would handle the contour of the pond wall perfectly as opposed to several angle to make the turns. Never used flex before so I thought I'd ask for opinions.
Thanks