Problem. Please help. Yellowing

so i looked at the faq about plant problems and those pics need updating.
Heres the leaves on the bott0m of my plant.

Any ideas what is wrong?everything has been the same untill this started happening 3 days ago. one turned yellow then the rest did. bleached yellow.

root lock? Nitrogen deficit? help.

Thanks!!

try just water for now or get a cheap NPK test kit thats what I did and it helped to at least ease my mind and rule out deficiencies..................

are you about 1/2 way thru flower? looks like nitrogen def. to me. mine always get like that towards the end of flowering

Hey man im almost positive, that looks like a Magnesium Deficiency .. Leaves turn yellow and veins remain green.. text book magnesium def.. try foliar feeding with some epsom salt.. resolved my issue.