ReefRhythm - Advance Stepper Motor Controller with OpenSource

[BDH]

You don't really, as the tubing also plays a part here. Using different tubing (e.g. a stiffer rubber) may work.

Most pumps of this fashion require some calibration to ensure more equal flow rates.

This makes sense. And of course I can change the flow rate with the controllers if I go with the two pump system. I was just surprised at how far out they were, all other things being equal.

 

[BDH]

In my opinion, the idea of a pump with double tubing only fits laboratories where lines are short, etc.

About your issue, I think pumps have different performance because of the of the tubing in pumps and the different line lengths.
But everything can be calibrated. Just calibration should be performed with a real setup. And if you have 2 pumps, for refilling and draining, they can be calibrated separately and it should solve the problem or at least make it less inaccurate

Very true. Once calibrated, do you find that they hold their calibration indefinitely, or is it something that will require frequent checks?

 

[theatrus]

Very true. Once calibrated, do you find that they hold their calibration indefinitely, or is it something that will require frequent checks?

Periodic calibration is required - the tubing will stretch and deform, and there is bio-fouiling, but the difference may equalize if both pumps are running the same amount.