[reddhaus]

I plan on using a Mag 18 and a 1" Sea-swirl for the return on my tank. The output of the pump is 3/4" and the fitting on the Sea-swirl is obviously 1".

Is it better to convert from 3/4 to 1 down at the pump end and run 1" hose up to the Swirl or keep it 3/4 hose up to the Swirl and then convert?

Will either of these combinations have any effect on head pressure and flow rate?

[Ltspd]

The 1" SS cant handle but 1150 gph where a Mag 18 puts out 1800 at 0 you need atleast 6ft of head pressure on the Mag18 to not overpower the SS (1100 gph at 6ft) or a BV to throttle it back some.

The Mag charts are developed based on their input/output pipe sizes so as long as you are 3/4" (mag output on 1800) out then it doesnt make a diffrence where you increase to 1" IMO,