Hydro week 8 of flower turning purple n curling

Is this a sign of something or just part of the process? Don't think she ready, (2-3 weeks?). Both my plants in RDWC are doing the same, but this smaller plant started sooner, and shows more purple. Bogger plant has more curled leaves the higher up they are on the plant. Lower leave have less curl. The purple shows mainly in the fans, but is starting to show on all leaves.

GH nutes 600pmm
SF4000+Mars hydro4000
Air 76° 50%
Water temp 68°-72°



Thanks for the help and advise as always, so glad I found this place it been a huge help! Some day I'll have less questions, or at least better ones.

Sorry if this is a dumb question. This is my 1st grow, and my 2 soil plants are not doing anything like this.

I've seen pics of plants that go all purple, but not this odd kinda half/half thing

Any thoughts are welcome.

Thanks.