4 strains

What is the ph of your water feed? While yellow leaves are a sign of Nitrogen deficiency, it's more often cause by a lockout due to improper ph levels or over/under water feed. So check the ph first. Going in, and runoff. Also, what is your tds runoff? Use your grow question so you can get a few answers. Don't wait any longer, your plant needs some help asap.

Good luck with the grow ;)