Help before flowering. Curling/ browning of leaf tips, red stems

Remember this is my first time and it's extremely amatuer.

Plant:
Master Kush from seed.

Setup:
Setup is in a crawl space 4x8x4 lined with aluminum foil.
Temp is on average 65 degrees F at lights off and 75 degrees F during lights on.
Humidity averages around 45% - 50%
Light cycle is 18/6
Using five 45 watt daylight CFLs, one directly on top, 4 on one side, making me rotate pot throughout grow.
Have both circulation and exhaust fans.

Medium:
Growing in Black Gold Cocoablend Waterhold Organic Soil

Watering:
Watering every three days (32 oz) with half strength nutes. Using cycle of veg nutes, CalMag, and water/ h2o2
Ph 6.5-7.0 using a soil test kit, although my last reading was 7.5ish so I added a tiny amount of lemon juice to bring it down.

Nutrients:
veg- green lightnin' organic plant food 12-4-6
earth juice CalMag for a deficiency I thought I had, but now using it every third watering
flower- going to use Kool Bloom 0-10-10


Stage:
Plant is 64 days into veg. Was planning on throwing it into flowering in a week or two.


Problem:
Bare with me please. What I'm concerned about is both the leaf tips curling and the brown spots also on the tips. The brown tips I believe I can contribute to nute burn (all tips are slowly browning on the bottom node) but I'm really worried more about the curling (been going on for a two weeks now). The leaves also sweat sometimes, so my understanding is this could be heat stress, but can it contribute to the curling?

About a month ago I started getting yellowing and necrosis of the bottom two nodes of the plant. I was also having gnat problems and reddening of the stems (I'm hoping this is from the temp change) at the same time. So what I did was flush, water/h2o2 (to get rid of gnat larvae, don't see larvae anymore but still see the occasional gnat) and picked up CalMag for the next watering.

After a week I lollipopped the bottom two nodes (first being completely dead), topped a second time, and damn did she love that. Started to look healthy again (until the curling started 10 days or so ago) and threw out female preflowers, yay. One other thing. Strain facts told me this plant won't grow over 50 cm or 30 in. That being said, will my 2.5 gal pot be able to flower my plant without getting rootbound? I'm looking for both answers/ suggestions to help my plant before I throw her into flowering within the next couple weeks. Thanks guys.

Looks great to me congrats. Thank you for the post .

I like that blue pot, very good vibes. I think you are doing fine as well. You read the claw signs correct. Those leaves usually don't straighten out again so you want to evaluate your newer leaves, which look better. I'd flower right now because you are going to be up against it space wise. If you veg her longer then I'd favor transplanting up.

It looks like too much nitrogen or overwatering but in my experience isnt a big deal especially if youre going into flower...i would let the soil dry out completely n flush before flower then switch to higher p-k nutes. The red stems could be magnesium deficiency,
I have noticed on my current grow that the buds in 3 gal pots are smaller than ones i have growing in a huge rubbermaid tub...3 gal is like minimum i think,
doh...couldve yielded more i guess

thanks for the input. So I think I'll transplant today... flush and flower this weekend.