I plan to have 3 levels to the pond system I will build with a head height aprox 6'. Main pond at the bottom, bog in the middle and a lilly pond at the top. Water will be sent to both the upper pond for fish and lillys and to the middle section that will be a bog. . Wondering about my flow rate when the top pond valve would be fully open and the middle one adjusted to allow the proper flow to the top. Will my flow rate be calculated for the total head height or will it be greater with 75% of the flow being sent to the middle bog section.