Hi Rodney

Have you got a bottom drain that has a connection for a 2inch pipe? The
only ones I've seen are for 4inch but I don't really take a lot of
notice of them.

Yeah its for a 2" or 3" pipe. Mine is connected to the 2" ABC pipe. I
added some more pictures and now you can get an idea of what it looks
like.

The water won't push up the pipe unless you have it sealed so that it
can act as a syphon and even then the outlet must be below the water
level at all times for it to work.

That's what I assumed so I think I will just install it similar to
what you can see in my last few pics that I took today and for the
most part I will use it for partial water changes.

Cheers,
Chris