Hydro-Plug/Hydrostatic relief valve

[mattmackay22]

Hi There!
We recently moved to a new home (new to us), and it was built in the 90's.
It has a pool, and I cannot find where the hydro-plug/hydrostatic valve is.
The pool has 2 main drains, with Hayward covers, however, all that is there is the 2 pipes that lead back to the skimmer, with no hydrostat in sight. There's something in the deep end that looks somewhat like a hydro-plug, but I can't see any markings and the plastic? portion isn't circular as I've seen them.

Please help as I need to drain the pool to do some maintenance.
Thank you!

Photos of main drain and what may be the hydrostatic plug (in deep end on side of wall):
https://photos.app.goo.gl/rLhteCYLQuzhp5f16

[Denniswiseman]

You may not have a hydrostatic relief valve as not all pools have them. They are there to allow ground water into the pool when it's drained to prevent floating

[nyleakpros]

The last two pictures are not clear enough to identify what we are looking at. But the picture of your main drain looks like the plumbing line is just coming through the shell of the pool without any kind of sump. If that's the case and you don't see any other items in the bottom of the pool then no, your pool does not have a hydrostatic valve.

[Teapot1]

Agreed.