Flowering plant leaves yellowing?

It’s happening very quickly and spontaneously it seems though. About a week ago she barely had any yellow leaves, and this week nearly 40% was yellow or beginning to. I opened the tent up today and noticed new leaves starting to turn :( I use tap water that I leave out for ~24hr for removing chlorine. I recently starting adding some lime/lemon juice to lower the ph to around ~6.8ish because before it was reading around ~7.6ish. I don’t think I’m using too much nutes though. I’m using FF Tiger Bloom + Botanicare CalMag Plus at maybe 3/4 the recommended dose. I also noticed the clawing near the bottom half and I don’t know what’s causing that either. I’ll pass just the water through it for the next week and see what happens.

5th week of flowering - could mean that she is just absorbing her stored nitrogen (and other nutes) starting in the bottom shade leaves and will continue up the plant until she is ready for harvest.

N-def unless it started interveinally then spread? i just don't see rust-colored dots, so i don't think it's magnesium def. p/k tox can display ca or mg symptoms check labels.. what are you providing? have you been feeding heavily or moderately? use that to eliminate possibilities. Fe def? do you use tap or RO, if ro, that's a maybe too. You have a robust canopy at moment, so don't think you have to do something tomorrow. If you have an EC meter, rule out overabundance to some extent. May sure pH is in range for your medium. do that stuff before adding anything.