The impact of tubing sizes

[spookmineer]

There is a depression at the pump inlet, this is a fact, an observation if you will, not an opinion, and not debatable.

I stand corrected (my assumption "The actual lowest pressure (at the suction side of a pump) might still be 2 ft" was false).
But I did not say there wasn't a depression at the pump inlet, I said it isn't a vacuum... ("going below 1 bar" is not the same as a vacuum).

In other words, "Their loop is more restrictive then the pressure from specs can handle, and the pump intake is indeed below 1 bar." is not an exception but it goes for all systems?
Or does depression simply mean, the location in the loop with the least amount of head pressure, but still more then 1 bar?

This depression causes vinyl tubing to collapse over time upstream of the pump inlet. This is also a fact, an observation, not an opinion thus not debatable either.

...? In a way, you are repeating my quote of you

Quick connects are only designed to work under positive pressure as specified earlier. The depression causes seal failure. Air will engulf at the seal. This is also an observation, not an opinion. Please take my word literally: I have OBSERVED this phenomenon in many systems from customers, employees, and my very own.

Please learn from my mistakes.

I believe you! If push-in fittings were designed for applications where pressure is <2-7> bars, it has no place in hardly any watercooling system (it needs 66 feet of head pressure??), with most pumps the push fittings would work below system specs.

Somehow I get the feeling my post is misread, I can't see where I am arguing/denying with anything you posted.

After reading a lot of threads (here and elsewhere) I still know almost nothing about this subject. I'm just curious about it, and perhaps annoyingly so.