der_wille_zur_macht
Team RC
I think I'm not explaining this well. 
Look up the pump you want to run, and find the listed spec for intake and output plumbing size. They're not always the same, so look both up. Usually, it's bigger than the fitting on the pump too, so a pump with a 3/4" fitting might want 1.5" plumbing.
Anyways, once you've found that, just make sure that the cross section at any point in your plumbing is the same (or slightly bigger) than the specified size. So if it lists 2" output plumbing, you'll obviously want to start off with 2" right out of the pump. Now, if you want to split that eventually down to 4 outputs in the tank, you need to pick the diameter of the piping for those outputs such that the cross section is a little bigger than that initial 2" pipe. If we cancel out all the pi in the math, a 2" diameter pipe has (1)^2 for cross sectional area, and a one inch pipe has (.5)^2 for cross sectional area. You can see that though we only cut the diameter in half, the area went down by a factor of 4. So, in order to have the same cross sectional area as a single 2" pipe, you'd need FOUR 1" outputs.
Make sense?
Oh, and to throw a wrench in the works - if you are using an OM or another device that diverts flow to a single one of those 4 outputs, then all the plumbing needs to be the spec'd size, since at certain points in time, the flow will only be traveling through a single output.
Look up the pump you want to run, and find the listed spec for intake and output plumbing size. They're not always the same, so look both up. Usually, it's bigger than the fitting on the pump too, so a pump with a 3/4" fitting might want 1.5" plumbing.Anyways, once you've found that, just make sure that the cross section at any point in your plumbing is the same (or slightly bigger) than the specified size. So if it lists 2" output plumbing, you'll obviously want to start off with 2" right out of the pump. Now, if you want to split that eventually down to 4 outputs in the tank, you need to pick the diameter of the piping for those outputs such that the cross section is a little bigger than that initial 2" pipe. If we cancel out all the pi in the math, a 2" diameter pipe has (1)^2 for cross sectional area, and a one inch pipe has (.5)^2 for cross sectional area. You can see that though we only cut the diameter in half, the area went down by a factor of 4. So, in order to have the same cross sectional area as a single 2" pipe, you'd need FOUR 1" outputs.
Make sense?
Oh, and to throw a wrench in the works - if you are using an OM or another device that diverts flow to a single one of those 4 outputs, then all the plumbing needs to be the spec'd size, since at certain points in time, the flow will only be traveling through a single output.
