Why are my leaves turning this color?

Dry amendment products like Down To Earth, Dr.Earth or Gaia Green all need time and the correct PH + microbes to help break down and feed the plants. If you are noticing a deficiency then it is likely a week or two old and the amendments need about a weeks time before they become available. This equals a lack of feed for about two weeks. On top of this if then you are supplementing Liquid fertilizers they can mess up the microbe life in the soil. not normally to much but has the potential. I'd try compost teas if you want to stick to the organic"natural" way of things. When your topping up the medium with amendments their ratios are a bit higher then expected. they tend to go anywhere from 1-3Tbsps per Gal of medium. I'm guessing your root pouch pots are anywhere from 2-4gal and would require 2-12Tbsp of product mixed into the top soil. Normally they make this ratio a bit higher when transplanting into new medium/pots. Eg. my Gaia Green is 4tbsp per gal of medium on transplant and 2tbsp per gal of medium on top dress. It is advised you top dress ever 3 weeks as the feed lasts about one month in the medium. I also add in a bit more soil/worm castings/compost when doing this as well as the top layer tends to get compacted and airy, I saw in your Diary your only using 1Tbsp and that is probably to low, check the suggested feeding on the box. One other note is watering, when growing with amendments you do not want to be overwatering or watering till runoff. This will wash away any available nutrients sitting in the soil. Next run try mixing in around 30% perlite. and confirm your soil is really soil, a lot of places are calling things soil as soon as they add in compost but its really more soilless with compost added. I have also grown with this with some good success. To tell when you need to water pick the pots up or poke them and make mental notes of what they feel like before and after watering. Gnats are a sign of to much water in the top part of the medium. BT products kill them out well, I also have had great luck with Beneficial nematodes. kills em in the root zone and sticky traps kills them in the air. two part life cycle killing spree. https://www.amazon.ca/Nema-Globe-Beneficial-Nematodes-S-Feltiae/dp/B01N5TYSFU Best Of Luck!