Stop feeding promix until you get consistently healthy growth.

Fish emulsion should provide enough N for them to stay green. Which probably means it is a cal-mag or pH problem. The brown spotting on the light colored, interveinal chlorotic leaves, makes me think it is a calcium-magnesium deficiency.

Supplement cal-mag, and dont use vinegar to acidify. Get some proper pH Down (phosphoric+citric+buffers) or simply some citric acid to adjust your pH. Consider using biological supplement products for rootzone uptake like Azospirillium or another mycorrhizal supplement, or something like Real Growers Recharge (Bacillus, etc)

Real Growers Recharge is legit, and would definitely help get some green back in a week or two. Highly recommend it especially if you are just giving your plants tap water.

Oh and try filtered tap water or starting with RO water. Tap water contains lots of chlorine which often forms chloramine and that can cause yellowing and stunt growth.

Good luck.