Flower Week 4 Issues

Hey guys
Just ending 3rd week of flower here..
My main plant in front leafs are dying near the bottom and yellowing.. I've laid off nutrients for days and that doesn't seem to help the color.. I have been adding cal mag to feeding..
The other two plans are fine.. just lower leaves dying . ..
Everything is the same between all plants .. water ph.. nutes etc.. Why would 2 be perfectly green then one yellowing??
Current nutrient
Every 4th day (per 4l jug)
4ml aqua flake a + b
3ml big bud
3mlVitamin b

Just started to add budd candy..
Water ph is 6.4 to 6.5
Lights are 12/12
Just added another 400w light
So total lights now are 600w(started with) + 400w( just added yesterday).

More pics

Please help? Anyone

ok so I see yellowing and some red spotting. Which tells me its probably not getting enough calmag. yellowing also may be from low feeding. also. once you get to about week 4ish or 5. you will naturally start to see the bottom leaves dying. don't let this scare you. its perfectly normal. infact it helps clear out some under growth the deeper into flower you get. Just bumb up your cal mag. give it time to recover and just keep feeding a bit at a time and go with your gut. your obviously doing something right. you have some amazing bud growth goin on. your doing good man just take it a day at a time

usually if the veins are yellowing as well. usually just means she hungry. maybe the fact that you haven't been feeding for days is causing the yellowing to further. give her some food. wait 72 hrs and then decide to go from there. YOu have a lot of bud production which tells me she is metabolizing a lot of food and nutes.

Remember for the first 3 weeks of flower your plants are growing. So stick with veg nutrients for say 2 weeks and then 1/2 in 1/2 for 3rd week and then roll on.

thanks guys! LOVE U!