Would you say this is an Iron def ?

I'm really sorry for the bad pics, will try to get better ones







This has progressed over 3-4 days from what i've noticed
temps have been a bit high in the res 25ish (only for a fews hours at a time) ph a little high to at 6.0 (now 5.8 for last 12hours)
i read the "guide to defiency" thread and iron def sounded like the closes but i'm never too sure and could do with some opinions

I'm assuming you're hydro since you say 6.0 was high, but should still be ok.
I think it looks like you need some N in there, are you feeding at all?

yes i am feeding, they are on vitalink a&b and last feed was at full strentgh and then this has happened lol

Hydro or coco? Curious... Looks like N.
edit: Nice dense grow.

It's hydro, nft and thanks, I checked the roots and there looks like some kind of salt build up on the roots
So I've emptied the tank and filled it with a very weak solution.
I've also noticed some nite burn on the tips