Okay I am going to try help you out here. It seems you went through the EXACT same thing I went through only just a couple of weeks ago. My seedlings started yellowing to a pale whitish color, especially from new growth! I will post pictures on here if you don't mind after this post.
>>>I bought the Fox Farms nutes yesterday and mixed 1 tsp of Grow Big and 1 tblsp of Big Bloom in 1/2 gallon of rain water. I then got nervous and added another 20 oz of tap water to this to dilute it
Okay based on the 'Soil Feeding Schedule' you are feeding at 1/2 strength during week 2, am I right? The full strength according to the chart is 2TBLSP of Big Bloom and 2tsp of Grow Big per
1 gallon of water. I think you might have gotten a full strength mix mix since you only used around .6 gallons (including the 20oz). This easily will lead to a nutrient lockout as it has happened to me in the past. I would flush out any plants you watered with this as soon as you can because it will only progress from here. But you may need to add a
key ingredient to your water this time! I'll explain below.
>>>There is a white something in the leaves of some the plants. Not all of them but two of the four White Widow Feminized are showing this pattern. I should mention that these photos make the stains look yellow more than white, but the stains are definitely not yellow, they are white.
Okay the photos above are showing me signs of Magnesium deficiency. Yes, even the two White Widow X that you have there. Magnesium can be locked out by a couple of things. One would be an excess of Calcium, which I highly doubt. The other possibility is a slightly acidic soil between a pH of 2.5-6.5. This may be the culprit of your lockout of Mg, leading to the yellowing/whitening of your leaves. The other seedlings are showing late signs of it. My seedlings never got to your stage, as they started to pale from the center outward like yours.
Gently feel your leaves between your fingers, do they feel 'glass-y' or 'dry'? This is another sign of this, especially in more mature plants like your WWXs. Notice the new growth, and how the green in between the veins is slightly paler than the rest of the leaf. These are early signs of a Mg deficiency in a mature plant. As it takes longer for an older plant to show signs of stress than a small seedling.
As I said before, slightly acidic water could be the cause of a Mg
lockout and this could be due to your rainwater as mentioned in the previous post. Another reason you could be suffering from a Magnesium
deficiency would be that rainwater (at 1-5 PPMs) would not contain any Micronutrients like Calcium and Magnesium. A rule of thumb to go by is if you used Distilled Water, Reverse Osmosis Water, or Rain Water you will need to supplement the plants with the lack of Ca and Mg every time you feed.
Now going back to the beginning, about flushing as soon as possible, I would add some Epsom Salt for now which is basically composed of Mg at about 1/2-1TBLSP per gallon.
But once again I cannot stress how important it is to know your pH before watering your plants. As you can see you could basically be locking out essential nutrients it needs to survive. In your case the FF nutrients might not have been the main source of your problem here, but a more basic one: your pH.
Please let me know if you have any questions Older Grower. I really want to see you get a successful harvest from this grow