X2 agri inject. We have some neptunes as well. But they are only 80 gal/hr Big agri inject is around 110 or so for us. They work great. Get a big stainless injection port, figure out what you pump is putting out, keep the screen clean and let her rip. Oh and check it often for holes in hoses etc. We flush out our pumps and pivots afterward. Have been doing it for decades, your putting enough water through the pivot the little bit of N is barely noticeable and if you flush, it doesn't cause any corrosion that we have seen.