I am re-plumbing part of my pool filter system. Previously,
a 3/4-inch metal valve was threaded to 3/4-inch PVC piping.
The PVC piping had a PVC male adapter, which fit into the
female threads of the metal valve. I am replacing the male
adapter but find it is a very tight fit. A lot of torque
would be necessary to get it into the previous depth.

I have a 1.25 inch metal valve connecting to a 1.25-inch PVC
male adapter with the same situation.

Do I just use teflon tape on the threads and then apply a
lot of torque until each PVC male adapter inserts at least
halfway into its metal valve?