I measure each gallon and if I have to add anything, its one to three drops of ph down. Thats been one of the selling points I always thought, the stuff damn near ph's itself. Even when I add the pk booster, its maybe another drop or two. My water is just tap, that has set out for a day or three. I too was scared of those large numbers of n in MC when first started, its beat everything I ever tried for growing. I too hit it hard during veg with 2.5 gms, then 5 gms with the pk booster for bout four weeks into flower, then back off to the 2.5 and skip, then eliminate the pk, finish up with sweet water, last week reg water, voile'. AGain, don't do resevoirs, but Im not seeing much difference in the formulas, other than they keep rockin whatever they are changing. I think they have the ratio figured out, imho, being the trick. My main colas explode on the stuff, once dried, even if seems a lil larfy or green, after dries, burns white, even the trim leaves. Ive also noticed now Im adding my homeade sweet all the way thru the cycle, Im not getting any hollow stems. Not main stems or branches. Not sure if the homeade sweet all the way thru or the megacrop, but I been running lots of variety and its the same on each. When I did use MC and no homeade sweet all the way thru, still had hollows. I think its the epsom salts in my sweet I make, I just mix epsom salts and blackstrap. But thats jme.