1st grow leaves are falling on only 1 plant

[Mile Higher]

I have 2 plants, 1 Angry Ape(AK47XGrape Ape) and 1 Vortex, that I am growing in my bathtub. The Vortex leaves have been turning yellow and falling for the past 2 weeks. The A.A. looks great. I am 1 week in on flushing with just a little molasses and water. Plan on just flushing the next 2 weeks with just Water. Under a 50X microscope the trichs look about 10-20% cloudy, less than 1% amber, depending on which part of the bud you look at. Not very many red pistils but that could be the strains. I think they are at least 2 weeks out from finish, but this is my 1st grow. Should I add some Nutes to the Vortex or just continue to flush. I have pretty much Defoliated the majority of the plant already and don't want my buds to dry up before they are ready.
The plants are in 6 gal pots with organic supersoil mix using Roots 747 soil. each plant has a 400W HPS lamp and 2- 4ft 56W 6500k side lamps. 9weeks of 12/12, 8 weeks in flower. they were under 400W MH lamps for 8 weeks of GLR veg cycle. For nutes I used Guano Super Tea Mix for veg and Advanced Nutrients Organic Iguana Juice Bloom for flowering all at 1/2 recommended dose once a week.

Yellowing leaves on Vortex. Stems also turning red.

Angry Ape just doing fine I think

 

[indica vet]

it is quite normal in late flower for some leaves to yellow as the buds draw on the depleting nitrogen supplies
some strains totally change colour late in flower.the red stems are prob just a trait of the plant
your plants look awesome mate good job im drooling lol

 

[indica vet]

if you are at 8 weeks flower now i would just continue to flush with water and molasses.

 

[Mile Higher]

Thanks Indica Vet. I will just flush and ride it out. I just got nervous on how fast the leaves turn color. Especially when the other plant got the same care and looks fine. Did not want to blow it being so close to harvest. I will just trust the Trichomes and wait to pull this plant.

 

[NuttyProfessor]

nice buds