Ok here we go again.... your problems are systemic(affecting the entire plant). First as an introduction Hi everyone and to followthelight. new to cannabis here, however, have a plethora of experience in gardening and botany. So now thats out of the way
You have a chance to fix your plants so that is at least a good thing.
It is agreed with what a couple others said on here....1.) Interveinal Chlorosis....2.) Toxic Soil..... but there are several causes for it which flushing will not cure.
So we can all see you are running about 6.8 pH which is okay, however, something is still preventing nutrients from your plants.
There are several causes for chlorosis, like nitrogen and mineral(iron) deficiency. Also consider root issues such as swamped roots and or root damage such as root rot.
What is strongly suggested is to do an immediate transplant into good soil, with perlite for best drainage and an organic one that is less prone to toxicity.
Or what will be the best, healthiest, and quickest way to help your plants recover if there is root damage caused by root rot, is whats personally called "transplant surgery"
Here are the steps....
1.) Purchase Soil, your budget's choice here but if you are looking to start your plants off in the healthiest direction get Fox Farm Ocean Forest. About $18 per 1.5 cubic ft.
2.) Purchase Deer Park Natural Spring water in gallon jugs (Why Deer Park Spring Water?) Because, it is usually around 6.6 pH and has good minerals in it.
3.) Purchase Superthrive. Because it has vitamin B which will help your plants through any shock they have gone through and or transplant shock. About $10 at Walmart.
you could use a dissolved mixture of cloning gel or powder but it is way more expensive for about the same result.
Transplant Surgery-
Step 1....Tap sides of pot to loosen up soil then hold stem firmly between one of your fingers as you palm the top of the soil then flip pot upside down and tap on bottom of pot to get rootball and soil to release from the pot.
Step 2....Set up about a wide enough platform of sterile papertowels in sterile bathtub, so as a rinsing platform. Set the potted shape clump of soil+rootball on the papertowels.
Step 3....Get your gallon jug of water and add 4 drops or 1/4 teaspoon of superthrive to the gallon of water then shake to mix thoroughly. Then while holding the stem in one hand very gently rinse off soil from roots a little bit at a time from the outer edge and work your way in. If you notice any rotting roots get rid of them by cutting them off with scissors.(Roots should be white to lightly grey, if they're black and slimy (not from the soil) then they're dead already and you don't want them to continue to rot the rest of the other roots and eventually kill your plant.)
Step 4....Once the roots are clear of any of the old soil, lay the plant out on some more sterile papertowels and mist the roots with a very diluted solution of Hydrogen Peroxide and your bottled water(1 tablespoon in a 20oz sprayer shaken to mix thoroughly), just enough to wet them down, and sanitize any other healthy roots that may have come in contact with the other rotted roots and soil.
Step 5....Having also prepared a much much larger pot to transplant in(the one you'll use to complete flowering, also having rinsed hands off in rubbing alcohol as to not cross contaminate new soil) layer about 8-12 inches of new (DRY)soil on bottom then create a bowl shape to the soil.
Step 6....Take your plant by the stem in one hand and have the tips of the bottom of the roots touch the top of the layer of soil in step 5 and hold stem still by using your forearm as a resting point to keep the level of height and where the bottom of the stem should be sitting about an inch below the top of the pot.(Why your forearm? Cause its gonna take a while and it will get tiring trying to hold your plant still the entire time you fill the roots in with soil.)
Step 7....Handful by handful keep sprinkling soil till you have reached the base of the stem.(Reason behind this is to make sure you have filled in your root system without tangling roots all together and keeps them spread out for better water and nutrient absorption.)
Step 8....Now while still holding the stem in place tap the pot down with your other hand gently about 4 times to loosely compact the soil around the roots to give them a better foundation and more stability in the soil. (Add more soil at this point if necessary.) Then see if the plant can stand on its own,( if it is still a bit shakey then still hold on with hand,(DO NOT USE a stake to tie to the stem to hold plant up this could damage your roots or worse your taproot.)
Step 9....Take sprayer used previously to mist roots and spray onto top of soil till moist, and sterilized. (DO NOT SOAK IT remember it has diluted H2O2 and you only need so much of it) (BTW spraying the top of the soil with water will help better evenly distribute water to the soil so when you water your plant in this situation, the water doesn't just float all across and get absorbed by the soil unevenly and may not get to all of the roots.)
Step 10.... Take your gallon jug of water + 3 drops of superthrive(Mix/shake up) and starting from the outside in start slowly pouring around the edges of the pot and work your way in (SLOWLY). Again, the reason for this is so that your roots will get watered evenly and also that they get settled in firmly for a good foundation to support your plant.
Step 11....After about 5 days (or until the plant has wicked most of the water out of the soil) then you can start to water again. Until then keep your lighting schedule 20/4 or 24/0 so the plant can start to recover and start to use chlorophyll and photosynthesize itself blah blah techno babble etc... LOL
And that's about it... Yes, very painstakingly a long process and if you do have the patience and you want to have the best chance for your plants to survive and recover then take the time to do it right. Otherwise, if you let your plants continue like this they're going to die for sure, so why not give them a fighting chance.
Sorry if any headaches were a result of having to read such a long post LOL
, but trying to help as much as possible.
GOOD LUCK....
