The damage to your pool pump will normally many times the cost of renting a pump.
Swimming pool drain.
This is a one way spring loaded valve and when you drain a concrete or a fiberglass pool you should remove the hrv until the pool is ready to be filled again.
While sucking from the main drain and putting the water down the backwash line will work in some scenarios it puts your pool pump at risk of losing prime and running dry.
If you cannot locate a hydro static valve call a pool professional to drain it.
During normal operation water flows to the filtering system through two or more main drains at the bottom of the pool and multiple skimmer drains around the top of the pool.
3 it is not recommended to drain a swimming pool through the backwash valve.
A pool s so called main drain is not actually a drain.
5 every foot or so of water level decrease spray the perimeter of the pool s previous water line with a hose.
That is it is not used to drain the pool.
All concrete and fiberglass swimming pools should have a hydrostatic relief valve installed in the main drain.
The main drains are usually located on the lowest point in the pool so the entire pool surface slants toward them.
Instead it is an outlet housing a pipe that runs to the pump which sucks water through a skimmer then through a filter then through a heater if you have one and then back to the pool via multiple inlets.