have you flushed? what is the ph of the run off? if it is anyting other than 6.0 or very close then your soil ph is off. flushing will sometimes help, but mostly it is salt build up that starts to happen and this caseues improper ph's and in turn caseues nute lockout.

if your ph is ok goin in and out then try some cal mag, even though I dont see any spoting, your deficient in something. so either the bucket has something wrong such as soil does not have enough dolomite or improper phing of water and nutes. Or your nutes are missing something. since your not in flower I dont think your needing a booster. but mabey your nutes are also not strong enough?

deffinecy in something