Yellowing Leaves

I have a plant that's 2.5 weeks old and the bottom leaves are starting to yellow a bit. I'm wondering if she's ready for some food? So far I've been feeding her plain, filtered (hard) water. PH of 6 and PPM around 400 (no nutes).

Should I feed her a little? Like 5% concentration? The nutes I have are technaflora, the starter set.

Here is a pic from today:



Here's a link to her photos throughout the grow so far:

http://www.growkeeper.net/growurls/caligabe/?plant=19&reverse=True

Thanks for any suggestions!

Caligabe

Yep. 2.5 weeks from the time I put the seed in the rockwool. So maybe closer to 2 weeks since sprouting.

And yah, my plain water is close to 400 PPM from the tap. Sucks. I should invest in RO... But already bought an expensive filter... Think the guy at the shop didn't really know what he was talking about cuz he said the filter I was buying would bring the PPM to 0 and I didn't know any better.

Do you think I should feed it a little?

She was under T5 CFL's until three days ago. Now she's under a Digilux 400W MH.

how far away is the light? Some times when you go from CFL to HID, the leaves can "bleach", where they turn yellow/ white even. The plant gets used to the low intensity from the CFL's and then they get shocked when put under HID......

Just a thought, this has happened to me a few times

The light bulb is 2 feet from the plants. It's in a cooltube with a 4 inch fan sucking air through it. The room stays in the mid 70's all day and the "canopy" is always in the low 70's.

What can I do to stop it from bleaching? Will it kill them? The reason I thought it might be a nute issue is because it's the lower leaves turning yellow.

if its the lower leaves or every where its a nitrogen deficiency, if it starts at the top and stays at the top its usually bleaching. if its bleaching that destroys chlorophyll. so raise the light