Theo has it correct. You can make the run of 400' with 3/4". Any larger pipe in the 400' distance is okay too. We just ran a total of 750' for a 3/4 hp rotary pump. System has 450' of 3/4" with 3 laterals of 1/2" and then 300' of 1/2" to last diffuser. System is operating 4 membrane diffusers and all working good.

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