Whem my sprouts turn purple It was due to too many hours of light.
The yellowing was too much water.

It seemed that my purple leaves burned out faster than the green ones but I cut the light down to 12-14 hours instead of 18 and my plants were fine after that.
8 inches would only be too close if you were drying them out from too much heat from the ballast.
If your using a shop light fixture that was set up for T12 lights you might want to change the ballast to one for T5's.
A T12 ballast could get too hot and your bulbs and ballast will burn out faster using the wrong ballast.could be a fire hazard too.

Electronic ballasts last longer and so will your bulbs.They will put out the bulbs best spectrum-one they were designed for with the proper ballast too.
A t12 ballast will over amp a T5 bulb.
For a while it will look brighter than with a T5 ballast but it burns out the bulb faster.

here is a link for the cheepest ballasts I've found.
They have other ballasts so look around the site.
Scroll down too for lighting info...

http://usalight.com/t12-fluorescent-electronic-ballasts-c-242.html

Info on Fluorescent lights and ballasts.

http://www.repairfaq.org/sam/flamp.htm

Probably more than you wanted to know. LOL
Hope if it's a light problem this stuff helps.

If I remember right, plants need 5000k - 5500k from a bulb.

Color Rendering Index (CRI) refers to color rendition, specifically, how the color of an object appears under the artificial light source illuminating as compared to natural outdoor sunlight.

Color Temperature refers to the quality of light emanating from the artificial light source. (Represented by by the number of degrees Kelvin based on the Kelvin color temperature scale.) The color temperature of outside light varies from 5000K to 6000K depending on the time of day, weather, season and latitude. The higher the color of a fluorescent lamp, the bluer (cooler) the appearance. The lower the color temperature the redder (warmer) it's appearance.

Color rendering index and color temperature are independent of each other. It is also possible for two different lamps to have the same temperature and yet have a different color rendering index.

Plants use one color to grow and one to flower.

I use 40 watt T10 bulbs that put out 6700k,3240 lumins.Good for 48000 hours.
My plants grow and flower under them.

Here is a link that might be useful: bulbs

I will try cutting the light cycle from 16/8 to 14/10 and see if it helps. The 4 bulbs are 54W T5 flour with 5000K as the color. They are currently in an electronic balist that is made for T5 and I am actually using the bulbs that came with the ballist. I will also try cutting the water back. I had been using a moisture meter but I am concerned it may not work (always says soil is dry) I tried putting the probe in a gallon of water and it read slightly dry? I hope my problems are simple ones as you have described.

At what stage do you start using mild fertilizer (ie tomato food at 1/4 rec strength)? Been only using tap water as of now. I did have a mold problem and had used alot of peroxide. closet temp is 83 deg F. Temp is from slight warmth coming from top of ballist. I have been using damp rid in the closet to control the humitity. would i be better leaving the door open? Or is the reflected light from the door helping.

Thanks for your very informative reply.

Jeremy

the purple veining is your plant telling you it wants phosphorous. the yellowing is the plant telling you it wants nitrogen. your plants are begging you to fertilize them.

I start using fish emultion fertilizer and seaweed extract at about 1/8th strength as soon as the 2nd to 3rd leaves form.
I don't know if I'd use chemical fertilizers as soon.If I did I'd use really small/dillute doses at first.
They can build up fast.
Organic stuff usually has to somewhat break down into usable forms for the roots so it is harder to overdose plants with it.
Also other stuff uses it too, like the biological stuff that grows in the soil.
Epsom salts also greens up plants- Magnesium sulfate.

If you think you have a fertilizer problem the chemical fertilizer should give you faster results than fish emultion or whatever.
Just make sure you flush your plants every once in a while with water to wash out the excess.

Since you had mold problems I think it may be an overwatering water - humidity problem.
A closet doesn't allow much moisture release.Maybe just crack the door open and see if it helps.
I'd still try giving them some fertilizer too in light doses,maybe a touch of epsom salts too.

Thanks smokemaster and shelbyguy.

Jeremy