Purple Leaves?

My plant is currently at day 10 since germ. The plant seems to be coming along ok , but theres a problem, i've been running a 42w 2100k CFL 24/7 with a fan blowing right on the plant and upon looking at the leaves i see purple on the underside and stems . Is this caused by a K deficeny how can i cure this. I don't have a pH meter yet but it will be here wthin a couple of days. Also today was the first day i changed the water in the reservoir and added nutrients for the first time

 

I dont think its a characterstic. today i looked at my plants and it started new growth but the leaves have become a little yellow with tthe stems turning purple and the veins of the leave turning yelllow, i added epsom salts today hoping to cure what can be a Phospurus deficeincy, is there anything i can do to help it heal faster.

 

soil: Perlite and hydroton mix.
nutes: GH flora series
what type of lights:42w CFL warm spectrum and a 15w T5 white spectrum(soon to be 400w HPS with MH conversion bulb)
what is the lowest and highest temperature in the room:75-80 f
what strain are they: White Rhino
what size pot are they in: 3 gallon aereated pot
how tall are they: one is 5 inches and one is 4 inches

Also i believe it was a phosphorous deificency because now it developed brown leves on the bottow but the new growth is green and looking fine and stilll growing larger...

 

I still don't have my pH meterbut it should recieve it soon. My plant seems to have recovered, tight now the plant is only two nodes tall and is 13 days old