I to run a nft i would hold back on the nuits and a top tip from me is to get some kind of air into the tank, growell have good pumps i sit mine near my pump they always seem to love it, you could also turn down your pump just have a small trickle coming out and change your water every 2 weeks atleast, a trunchin is also very good to work out whats in the tank, people make the mistake of keep toping up the tank but you dont know whats still in the tank, i do 1 top up with feed, then a top up with water, seems to work, at the end try stuff called 13/14 its a flower boost and must only be used once 3 weeks before harvest, i have used this stuff for about 7/8 years its very good, see growell site, also clean your pump atleast once a week, hope this helps, welcome from scotland,