Stealth have you checked the ph of the runoff on the SNL x NH?

Mine will do that too.....but immediately stop when I transplant them into fresh soil.....I can toss up a pic of my soil ones if you want....they do the same that but, again, always stop when I put them in fresh soil so perhaps try a transplant?

Also had some bugs....whiteflys etc sneaking in the house at night (in the living room....not the bloom room thank goodness) so when I sprayed my plants with bug spray they improved alot as well. BUT I think your yellowing is a soil/ph issue.