Sorry you learned something the hard way. Inflating the bladder from open air can lead to other overinflation problems, as there usually is no pressure sensor, to shut the pump off.
Another (almost opposite) problem to avoid, is to NOT remove the bladder hose from the end cap when bench testing, in order to deflate the bladder for another inflation test. Eventualy you will run out of air in the closed cylinder, and erroneously think things won't work. It is a Recirculating system, remember, so signal the RCABS release valve inside the cylinder to release the air back in from the bladder.
In the closed system, if the bladder does not deflate quickly and completely, when the RCABS release valve is opened, then there is an air (and potentially a water) leak in the cylinder.
RCABS- It's easy to control your own bladder!