Hello Aquaholics.

Bought a brand new ultitube 5 pro with leakshield.
I think this is a nice gadget.
Now i have a problem to calibrate my flow sensor, because i have hard tube i can not obstruct the loop so i have different things to do.

Tap the water off,
Change the acryl to add a valve
calibrate
take the valve out of the loop

But then is the flow different because there is no valve obstruction anymore.

So what is my best option to do.

thank in advanche