AK47/Blueberry/Auto Flower

First time on this strain but I have done a few grows with greater and greater success. This round has me puzzled. A previous planting had a similar issue when one plant (California Hash) was moisture restricted. It was yellow and a bit stringy compared to the other plants (White Widow, Red Diesel, Purple Lady). Upon harvest I discovered the grow bag was considerably lighter than all the rest of the bags. Further research revealed that the drip emitter was not delivering the specified flow rate. Now I regularly do a weight check as well as a moisture level check to confirm water is being added to all bags in equal amounts.

Current plants show vigorous growth and serious branching and flowering yet the larger leaves from earlier growth are pale yellow to lemon yellow in color.

Most new growth is typical green of plants of the strain.

see attached images (these have an HPS cast, but even under white light they are only pale green at best)

I went though a period of low moisture when moving from seedling cubes to the grow bags. They didn't seem to be getting enough water and growth seemed to stop. I went from simple hand watering to drip, 1.5 hrs at 1gph every 24 hrs. Growth restarted slowly and the plants went from normal green to light yellow.

I now suspected over watering and set my timer from 1.5 hrs drip at 1gph every 24 hrs to 1 hr drip at 1gph every 24 hrs.

I read here that too much light can also cause yellowing. My light is a 600w and is 10-15in away from the plant tops. I see the allowable distance can be as little as 8in so I feel ok about light.

I also saw that heat can be an issue. My room is low of 72, high of 85 degrees F. I use CO2 (900-1200ppm), I understood that 85 degrees was acceptable.

Humidity averages 40% but can swing up to 80% for short durations right after the light goes off.

New growth has been green on all but the largest most robust plant. WTF? That plant has bright yellow leaves on even the newest growth tips! Even the Calyx pods are yellow.

Generally, branching and flowering are progressing at a rate similar to previous grows so I'm not unhappy.

Just curious. Do I really have a problem?

Attached Images

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