we just purchased the "USA 110GPD RO+DI REVERSE OSMOSIS WATER FILTER" unit and are having a really hard time getting the membrane to goin in 1/2 inch, lol... wont go past 1/4th inch... is there any way when we get this thing put together to test the water to make sure its actually removing everything before we start mixing it with salt?? Anybody have any suggestions on how to get it past the 1/4 inch ??