HELP! purplish stems and leaf tips brownish/purple

Hi i have an indoor grow using soil with 400w of cfl. i have noticed that leafs are getting purple/brownish tips.. this happened about a week ago i have recently added more lights making it 400w. it seems to be getting a little better. i also recently transplanted it into new soil as the ast was hot in nitrogen. It is looking healthy and i hear that some plants are genetically purple stemmed and it gradually turns green/brown. I just dont want to give it any treatment it doesnt need. Im using tap water and the ph is around 7.0. As you will see from pictures.. the bottom part of the stem is perfect but the top part is slightly purple.. it does seem to be getting better. and as i just took the pictures the leafs have make a massive recovery.. but still im unsure.

only thing i have changed like i said is the lights and i have moved the a little further away..


heres some pictures.. any help will be appreciated thanks!!

room temp?

sorry I should have read further into it. tap water is no good for plants my dude. if you use it it has to be set out 12-24 hours prior for the chlorine to gas out. chlorine is toxic to plants.

room temp ranges from 26-30 tops! ahh ok then thanks i didnt know that!