First time post so be gentle.
I am in the process of designing/adding an in gunite spa to my existing pool. It am expect it to be raised 18" above pool level. I have read enough find that a Hartford loop on the air line is required. I have also read where some builder have them "IN" the spa wall. With these in wall Hartford loops I would assume the TOP of the loop piping touching the top of the gunite which puts the BOTTOM of the pipe VERY close to the water level. Example:
Base on my sketch if I center 1.5" SCH 40 PVC loop in the space between water level and top of gunite there would only be 0.705 inch gap between water and bottom of pipe opening and if the pipe is skew to the top of the gunite you would still only have 1.255 inch gap.
The basic question is how is the done in the real world.
PS I know I can create a loop outside of the spa area but it would be hard to hide and still would be 20' away.