Leaks outside the bag must be fixed before the bag goes down, or you are in for a lot of tail chasing.    Barbs, push fits and hose clamps all work, but whenever possible, include vac sealent tape and check they are air tight.     Easiest way is to place your finger over the end and feel the vacuum, then clamp it near the pump.  If the vacuum holds, it's good.  If not, find the leak.