i do have valves in each one. I have done what u said and after a few minutes 2 or 3 drop off and i get no flow. I know there is no blockage because i have tested each one individually and the flow is clear. the PB switched the pump Super pump ii SP3020X25AZ from the waterfalls to the pool and now its worse. the Super pump II 2.5 hp was good but needed a little more strength. Thats why I told him to put a 3hp motor but he used the older pump from pool i have and its worse. That's why I am wondering if the Pentair waterfall pumps would be better for these 6 sheers.