Got Pictures but need help on what it is please

You can see in the last picture the main parts of the plant its affecting, just need a confident answer
have no clue why this is happening i do regular res changes with vitalink a&b, tbh its starting to piss me off

Either the ppm is too low or the ph is wrong, must be 5.8 .

Ph is 5.8. Everything was fine. My background EC is 0.6 and it's only when I made my EC 2.0 I started to see this problem along with what looked like nite burn so for last Week I've ran an EC of 1.3-1.4 I checked it this morning And it's risen to 1.5. The problem seemed to have stopped but it's spreading again, What would be the best thing to do?

That's some jump from 0.6 to 2.0...try dropping it down for a while and see how she goes?
I never ran any higher than 1.60 when I did hydro, but that can be strain dependent as I've only grown indicas
Your EC changed from 1.3 to 1.5 because she drank more than fed...

I worked up to 2.0 I didn't just jump to it, so she's drinking more than feeding so why the problems? I guess they ain't under fed then?
Does anyone know what the problem is looking at the pics? Defiencies or not?
I add my background ec to total ec so if I say ec2.0 that includes my background ec of 0.6-0.8

the color change started at the tips and worked it way back, the weird thing is it worst on one plant than the other 2.
i normally mix my solution in a tub the add it to tank n save whats left n use it to top up for 2-3 days and then do a clean change. is that bad?

its working its way up the fan leaves, they dont seem to be drinking as much either
You can see it on the tip of the big fan leaf just starting

if your ph is in check, then maybe the vitalink sucks and is not providing a balanced diet.

yh maybe, my ph has been easy to control so must be another problem.
Would me switching straight to bloom nutes and cutting all the undergrowth about 2weeks in affected it?