I should know but i don't.

I should know but i don't.

Been looking at pic's and i cant find what i am looking. So it's over to the comunity to help cheers.

This could be any number of things, so far this grow has gone tits up.

1 I have give them nute burn
2 I have fed them water without dissipating the clorine
3 I have fed fluctuating ph'd water
4 The timer went the other day
5 They have even run out of water once
6 The heat has been high in someparts of the grow

I am growing white widow under a 400watt hps using the DWC method.

+REP FOR ANY ADVICE

Have you checked for bugs?? Looks like a spider mite infestation to me.
Check the under sides of your leaves.

You might have a few spidermites but that's definitely not all dry and burnt and crunchy from them mites.
It's either ph or nute burn, kinda hard to tell from the picture

Cant see any spidermite, will have to get some better pics tomorrow. Finger crossed i can bring them back as there in a bad way.

Some of the leafs are yellowing as well.

Sort of lost interest half way through this grow, gone have a bit of time off after this grow. Done 8 back to back time for a rest.