Everyone please run the calibration on each pump at least 10 times. On my pump #1 i was unable to get it to fill to the 100ml, then during further calibration running the pump got suck in the on position, im afraid that without the testing and just hook it up it could have killed my tank. I contacted reefbreeders, and they will be sending a replacement and a return slip for the one i have. Great response time on their part in resolving the problem.