Leaf tips burned curling down and yellow

[Slothasor]

The leaf tips are burnt and curling down and now has some yellow/light green patches. At first (2 weeks ago) I though I might have a N def so I overfed them.. then the runoff ppm was way to high and ph low (1300 ppm and and 5.5 ph) so I flushed a week ago and still having problems with new growth.

Please help

 

[GNick55]

what are you feeding?
how much?

 

[Slothasor]

I have been using the Fox Farm trio (grow and big bloom)... I would feed at around 1000 ppm but then saw the burn on the tips and flushed and haven't given anything since. (I did a flush a week ago.. a few days ago just a plain watering.. probaly needs another watering tonight or tomarrow.

Thanks