I have the AquaC Urchin pro -- in-sump version of the remora pro. Like what was staed just before, you want "dry" foam as AquaC describes it. Start the cup, I am assuming you have the black o-ring around the collection cup to level it, at it highesdt point and lower it slowly until you get a slwo build up of foam. Keep an eye on it, it takes the remora a few days to calibrate itself.
GL