I don’t know what’s going on here,the plant is missing out on something,I don’t know what
Black gold soil think this is my problem
Plants are being fed 1 teaspoon of grow big 1 teaspoon of big bloom ph is 6.5 water ppm is 40
Never had this problem using ocean forest soil
I haven’t been using any calmag,I’m wondering if I need to use some of the tiger bloom
Is the plant yellowing from the bottom up with the fan leaves yellowing as showed?
Show a picture of the plant itself please.
Mag and Potassium deficiency, in my opinion. SS/BW…mister 
Older leaves do occasionally yellow and die.
Fox Farm nutrients aren’t particularly strong nor are they complete nutrients. You may need to up your feeds considerably and/or add a calmag supplement, especially given your soft tapwater.
First step, though, check that runoff pH.
if its from the bottom of the plant that can just happen naturally from the light not penetrating that far and is normal, otherwise you probably have some kind of deficiency, I see the stem is very red as well
This would be my guess also, picture of the whole plant would help.
misterbee and vernal both i would agree with, we dont know where on that plant that leaf came from, also looks like more then one problem, the stem looks real purple is it a purple strain? As Enlightened said need to see the whole plant.
could be normal necrosis turned it yellow, but the purple stems and the gray spot…
Vernal said first step is to get runoff and check that ph, if you have a ppm meter i would also check that as well
Vernal nailed it. Check the runoff pH, does that Black Gold have lime in it? FFOF does, and that helps buffer pH in soil. I would water closer to 6.0 in soil too, 6.5 is a bit high IMO.
Purely based on the one picture and the limited information provided, it’s probably underfed across the board. Big Bloom has very little nutrition in it at all, Grow Big is only 6-4-4 and you’re only using a teaspoon per gallon. I use 2x that much of a stronger nutrient per gallon just for veg plants. Grow Big has no calcium and you have very soft water. My ppm is 350-400 out of the tap. Switch to a nutrient with calcium or start adding your own.
But, as is often the case, problems are usually interrelated.
And God said unto Abraham, test thy runoff water!
Your pH is also probably tanking because your water has no alkalinity. Like @Who said, those wine-colored petioles and yellow growth is a big red flag.
Here’s a gorilla glue and cream plants I don’t know what’s going on,should I give them more nutes I fed my plants the same amount of nutes last grow and didn’t have any of this shit going on
I have plants that will look exactly like that…when the soil is not “ready”. I believe the pH is high, and lack of mag. I reuse all my soil, and have a compost pile it all goes into. When I jump the gun and use it to soon, that’s how they look. Ironically, the buds have always still been great. (Hopefully we are on better footing brother 
)
My indicas never do it, but the sativa dominate strains let me know fast.
I just checked the run off water it’s ph 6.6
Was 6.8 before feeding the plants ,may give them some calmag
Looks more like Potassium deficiency to me … 
Feed those hungry girls,
They look to be starving, need NPK, cal/mag and the ph is outta wack.
Just my humble thoughts…
6.6 runoff is out of wack
I’m going to give them more nutes and calmag next feed
Big bloom has it in it
Do you have a ppm meter?
Test your run off next feed for ppm and ph. Could be in lock out… But they do look hungry.
Good vibes and good luck✌
Run off ppm was 836
organic soil?
Says natural and organic on the bag,
I’m doing something wrong just don’t know what it is lol
I’ve done my last 3 grows the same way same amount of nutes,but I was using ocean forest soil for those ,I feel like throwing them in the bin and starting over
