I think I might have done a mistake with the flow sensor. Input comes from below and in through a 90-bend and goes out and up through a 90-bend. Reading the manual it says that the flow should go in a straight line or the reading will not be correct and might actualy be totaly useless. I'm guessing that this straight flow has to be horizontal as well? Is there a certain distance the flow has to go straight? 5cm, 10cm... I don't have room for a straight line after the pumps with my setup, but I can get it to work if I rebuild the output from the tank, through 2 pumps and to the flow sensor with plexi-tubes. If it works with a vertical line I have around 25 cm's.

Also, at what point does the cooling fluid (I use DP Ultra) start to "foam"? With the flow meter showing ~125 l/h it starts creating foam (top 5 cm's), as in a bottle of coke when you shake it. At 150 l/h my whole tank (vertical 400mm Bitspower filled to 350mm) is almost enterily foam, just the bottom 2-3 cm's are ok.

Citation de "InfoSeeker"

The MPS Flow Sensor product page states the following:

Citation

Installation note:
For an accurate measurement we recommend to use a straight piece of tubing with a min. length of 5 cm before and after the sensor. The sensor itself should not be equipped with angled fittings.

As to the DP Ultra foaming, I am not sure. I also used the DP Ultra and have no foaming issues.
Did you add any additives, and/or Is all the air removed from your loop?

No additives. It's like pouring a glass og coke, it disapears after a while, not leaving any residue or the likes.