I have a large pond with fish - 40,000 litres. I want to ask what would be the best way to connect 2 pressurised filter/UV units to my pump. In parallel? - where the output from the pump is split with a "Y" connector to each filter and another "Y" to bring the output from the filters back to one pipe which then goes to a waterfall at the other end of the pond. Or in series - where the output from one filter goes to the input of the next filter and then to the waterfall. Would parallel be better as it would split the pressure from the pump to each filter allowing the filter and UV light more time to work? Any thoughts would be greatly appreciated. Thank you.