It shouldn't do that, something is not right in there. Make sure nothing is backwards, it shouldn't go together backwards usually. Check for plugs that need removed make sure the check valve is the correct direction. Check for kinks in the lines. Make sure the in pipe is the in and the out pipe is out if you took them off. You did use the correct filters and membrane for your brand, no substitutes? Is this your first time or have you done this sucessfully before? Check here http://www.waterforliving.com/Troubleshooting.html it talks about adding air maybe that's your problem.