Didn’t see this coming, 2 weeks into flower. Watered my autos on Tuesday, and did another round of LST. They all look perfect. Some of the best I’ve grown. Looked in on them yesterday, all is fine on the western front.
This morning I peeked in before breakfast, and oh, oh!
Several large fan leaves have signs of yellowing. They were scheduled to be fed today. Mixed some Tiger Bloom, Calmag, and pHed the water to 6.5.
Open the tent, a bit worse than I thought. One plant, the smallest is fine. The other three have yellow or yellowing leaves. On one plant the yellow is moving up to the upper leaves.
Looks like nitrogen deficiency. As I said, I fed them Tiger Bloom, Calmag and pHed to 6.5. Tiger Bloom is a nitrogen rich food, that I’ve had great success with in the past. Soil is FFOF, light is 1000w HPS.
Will these plants survive?
I would suggest to do a soil slurry and check your soil ph and ppms before we start throwing stuff at it. Are you following a flushing schedule?
Fox Farms trio is meant to be used altogether, Big Bloom, Grow Big and Tiger Bloom. I would suspect nitrogen is lacking, but there are probably other deficiencies working on showing up.
I give tiger bloom and big bloom with just a touch of grow big during first half of flower. Second half i cut out the grow big to avoid some fox tails.
Just curious how much tiger did you mix per gallon.
Pictures truly help
7mls or about 1 tsp.
Pictures please
Wow sounds like they are starving compaired to what I feed.
Also, it is recommended to start at half the dose and gradually work up to these feedings.
Agreed 
Just a suggestion, but an important one that is easily overlooked. Make sure whatever you’re using to measure your PH is Calibrated. I learned this the hard way after chasing everything else. Especially if you’re using an inexpensive PH Pen. Mine held accuracy for only a month. It ended up off almost a full 2.0 too Acidic. Also, I’m sure many also have great success with FF but I had issues and ended up switching to Jacks nutrients due to a suggestion another gave me. I find it way easier (at least for me) and cheaper.
GDP Auto two weeks into flower below:
I have a Bluelab pH meter, and I calibrate it. Matter of fact I just purchased new 4.0 and 7.0 calibration liquid. I’m confident it’s ok, but thanks for advising. 
I’m more or less convinced my problem is somehow related to expired FF trios. This is why I switched to maxibloom.
I noticed some of the FF needed to be shaken hard to fully mix before dosing. Another confession of mine. 