Yup deffo N hungry, Iv heard mixed reviews about M G, but iv never used it so not gonna say if its safe or not.
How long have your plants been alive for? Looks like you'v gone a bit crazy with ripping all the fan leaves off on one of them.
The proper way to have gone about this is to have Bloom and grow feed ready before you started the grow pal.
Because as soon as you see the leaves start yellowing that was the time to add some N into your nutrient solution.
With autos i feed N from say 2 weeks up to 3-4, then the bloom.