Nute problems in flushing stage?

[Str3aks]

Hey, GC, I've got a problem I'm hoping you can help me with. I started flushing with pure water 5 days ago, and the upper leaves are starting to turn yellow, and dry up around the edges. I know the leaves will turn yellow as the buds suck nutrients out of them, but this doesn't look much like what I've seen in the GrowJournals on here. Pics are below, and there's more details so you can help me out.

What type of medium; hydro; DWC
What strain? bagseed, Indica structured
How old are the plants? day 48 flower; 60+days veg before that
What type of lights and how many watts? 6x 26watt soft white CFL's
How far from the lights? about 3"-4" away from cola
What, how much and when was it fed? Hollands Hope trio, until 5 days ago
What is the medium/runoff pH? ~6.0-6.2
What are the temps and humidity in the room? (hi/low) Temp: 83/68; RH: 54/33

There's a link to the Grow Journal in my sig, if you want more info, or I can answer questions. I'll be posting a couple more pics on there, if these two aren't enough. Please let me know what you think, GC. Thanks in advance!

[Str3aks]

I found some more pictures on my camera. The first two are from 2/23, the last two are from 2/25. The problem started at the edge, and I guess more brown that I remember.