Shower Drain

[lochcarron]

Just about to install my shower base in my basement bathroom. Are the no caulk drain seals reliable or should I caulk around the drain and pipe as well.
Also my drain has to sit inside my concrete floor . I left a square opening to do this in my floor.Should I cover up with concrete or leave it open so if the shower were to leak it would drain through the gravel under the slab.
Any help would be appreciated.

[Dunbar Plumbing]

Use the all brass no caulk drains. Make sure the hold down nut is tight.

I would leave a small area open around the drain but not if you have water issues.