I am definitely new to pools, but is your pump supposed to be the last thing before your return??? My setup goes 1.) skimmer 2). pump 3.) filter 4.) automatic chlorinator 5). return to pool. I thought the water went through the pump before hitting the filter. Maybe someone can help clarify this for us. As for your original question, we had water leaking out the top of our chlorinator too, but DH just super tightened the cap and it seems to be better. I don't even know what a Nature 2 is so I can't help ya there! Good luck!