Some leaves turning lighter shade of green, fading

[40 years since first grow]

Not sure what is going on with my 2 girls in their 5 gal pots. They have been doing well up to about 1 week or so ago. They have been outside since about May 20th. Looking pretty good overall. Lots of colas /bud sites. Soil is a mix of MG potting, sand some scoops of coffee grounds egg shells and banana peels, not composted rather fresh, but not much in the mix also some ProMix peat and a bunch of perlite.
They get watered about 1-2 litres a day. They may have been over watered one weekend while we were away. Fertilizer has been a MG 12-4-8 weekly. I have also been using sporadically for the past 4 weeks or so a mix of vinegar and water ph to 6.2 or so. The girls in the ground seem to appreciate it. So I have switched to a PROMIX organic 12-6-6 this past week. I'm thinking I may be seeing a Nitrogen deficiency based on my research, but being a noob I would like to get some trained eyes. These are 2 different clones, one was labeled CK and the other labeled Cheese. There is definitely something else going on with the leaf sets, a mix of 3 and 5 points. Starting to see more 5s popping. I feel good about that.

 

[InTheShed]

Nitrogen deficiency starts showing on the lowest (oldest) fan leaves, so if you're seeing paleness on the younger leaves, that could be the start of a potassium lockout from all the nitrogen you've been giving them.

You're feeding some really high N fertilizer, not to mention that the MG soil might be the kind with fertilizer in it already. I'd try to find a nutrient that was designed for cannabis rather than general garden plants. There are a lot of different brands out there.

 

[40 years since first grow]

The MG is an extremely low NPK ratio and the mix of soil with other substrates (sand, peat perlite) would most likely lower this more. I have added worm castings as well have given them worm casting tea on occasion. This is similar to what I have given the girls in the ground as well. The girls in the ground are a solid lush healthy green, one has been getting attacked by leaf hoppers, slowly getting this under control. All four get essentially the same treatment. I tried to capture the colour fade in the leaves in the pics. The fade is noticeable and concerning. The new growth looks healthy and green. The MG states to feed weekly as does the PROMIX. I feel the fading means they need more N, but this worries me as I have been giving them lots I think.

 

[InTheShed]

I don't recall ProMix mentioning how often to feed (I'm in ProMix HP and feed every watering as it's an inert medium). I would find a different nutrient and feed with every water. That way you know the plants are getting a balanced diet.

 

[40 years since first grow]

Intheshed thanks for your reply. I have switched to Bontaicare KIND and now that they are flowering just using the base and bloom, feeding pretty much every day. Still the one plant, a clone labeled CK (no idea of the strain, Cheese Kush? Critical Kush, Cancer Killer?) does show the yellowing leaves. Not too concerned at this point. The colas and buds and trichomes are looking nice. This one is the first in flower. Started about the first week in August. I still have one not quite fully in the flower stage, starting though. I have now started to trim the bigger leaves to get air and sun inside them. So far so good. Not the greatest of pics but each is bud/bush for one plant.