They look rough as fuck mate, so forget the every few days thing i said earlier at lesser amounts they really need feed as fast as possible and looking at size of those now in pots they should easily be able to take lots of ferts running through coco, so daily feeds @ 2ml a ltr is gonna be way forward to get these right quickest way.
So today looking at those if they were mine I'd really soak all coco to run off which may take 3 to 4 litres to start with and then just do the daily feed thing, which then may only be around 1 to 1.5ltr through each pot to a little run off each feed. Those plants even though they looking deathly they will have roots for size they are to be able to do all this. They`re looking really rough though mate, im sure you'll sort it though no sweat, not much to lose though Benji. You should notice improvement up top higher firstly within 2 to 3 days.
 I’m sure you’ll drag them back to full health , happy growing hun 