Please Help!!! Problems with plants

Growing in foxfarm ocean forest with no added nutrients, under 450 watt mh, leaves are curling on the edges and new growth seems yellowish, can't figure out what's going on at all. Had to come on here to try and figure it out I thought mg deficiency and watered with 2 tablespoons Epsom salt dissolved in a gallon of Ro water yesterday.

Anybody out there?

Its because you used RO water .... I use tap ( which has minerals intact ) not stripped out.
Your tap ( ppm ) will vary based on how your municipal water is setup , but it works fine , i mean you water your grass and plants outside with the shit ... Right ?

THEN if plant acts wonky ( cal mag issue ) i SUPPLEMENT more.
FFOF has enough nutes to carry your plant well into week 5 before showing some depletion.

Thanks I appreciate the feed back, so next time I water I will use tap water (I read somewhere using Ro was a good thing) thanks for clearing that up. Also should I start using nutrients after that 5 week window? (Which do you suggest) I just recently got back into growing have been on hiatus for a while and not really up to date on anything thanks again.

Anyone think it may also be stressed by the metal halide?