deficiency help

Hey I'm still new to hydro and need some help with these 4 plants showing deficiency or lockout.
1000 watt air cooled tent, no co2 master kush.
3rd week flower ppm 540 ph 6.0 drops over the week to 5.5, water temps 71f running compost tea. roots tan but no bad smell. Room temps 70f night/day time 83f.
Cultured solutions following the bottles instructions, I use to use lucas formula this came with the system so thought I'd try.

here are some pics
http://tinypic.com/r/2i9ie8l/8

http://tinypic.com/r/2rxcvi9/8

It seems to be on younger leaves more so than mature ones.

did u try calmag?

If your roots are fine and you're keeping ph in check, your plant is probably just hungry. Up the ppm

I have not tried calmag, I have read that cultured solutions does have calmag issues. I didn't think that looked like calmag but should I give that a shot?

Edit: I do not think they are underfed because the tip showed slight burn and I backed off, but it might have crept up a bit, can overfert cause that discoloration?