Problem with plant (need help)

Ok so this is my first grow shes only 19 days old since sprouting,
and shes been doing good untill now.
At first it started out with just some minor yellowing but now some of her tips are turning brown,

Here im going to list all i can,

Im growing in coir,
Ph is at about 6.0
I am using fox farms nutes,
2 6500k cfls, 1 2700k (65w,24w)
temps Lights on 88-90, off 73-76
deerpark spring water.

The nutes are now at half strength i started with 1/4 6 days ago.

Also she is a blue widow fem

Here is some pics to show what i am talking about also sorry that their out of focus i am using my cellphone and like to focus on the coir.

Too warm and the PH has to be 6.5 .

ahh i was wondering if my ph was off dident know if i should treat it like soil or hydro hopefully this fixes the problem going to have to get another out take then for the temps should be fun since the cab is metal.

If you make sure all feeds and watering are 6.5 you wont have a problem and try to get temps to 80, be easier in winter.

i added another fan to my outtake and got my temps down to 81 with lights on and i dont have a electronic ph meter but its at about 6.3-6.5 hopefully where all good now ^-^ thanks

dont feed it any nutrients until it gets a bit bigger

whoa buds he said hes in coir. ph needs to be 5.8 for coco

id say flush the nutes and dont feed for awhile

So wait should the ph be 6.5 or 5.8? and as for the no more nutes will do and ill try to flush her later today since its almost 5am here and im pretty lazy =p

if your in coco 5.8

a simple google search will back that up

ahh ok thanks