Is it a diaphram or impeller type pump.
 Washdowns are usually diaphram self priming and therefore doest matter which way they are mounted above water line.

 I dont know anything about 'tubes, would imagine they need a reasonable volume go thru.
 Diaphram are usually more high pressure lower volume (????)

 The spec in the instructions will give the details  mounting and wiring size requirements... and can download

Steps if you don't know anything about it don't post anything but instead you have to be an expert on everything and piss everyone off.

Mate I am sure so many people don't reply because he knows best abd can't be arsed. Do much of the advice given is do wrong abd I have done 25yrs in the industry so may have a slight clue.

So pump installed, and works great.

To get forum back to what it was, we need to contribute. A wealth of information out there.
Usually what I want to do has been done has been done by some one on the forum.