The plants are 3 weeks away from being done, I've increased the dark period to 13/12 anyone got any negative comments on this?

I've heard burning a candle can make a little difference with co2 anyone tried it?
KHAN Reviewed by KHAN on . 2nd Grow - Chronics flowering These are my Chronic ladies, 6 weeks into 9 weeks of flowering. All is going well i'd say, there is suprisingly little smell from them, I thought maybe because they're clones? Anyways, the leaves are showing a little bit of curling upwards on the edges of some of the leaves, the edges of the slightly curled edges are a light color. Isn't that mag. def? The p.h is 6.0 Rating: 5