clones stems turning purple lower leaves turning yellow help please

hello
this is my first try at cloning i put my cuttings in rock wool cubes and they looked good green and vibrant for the first 6 days today is day 7 and ive noticed the stems turning purple and on a few the botom leaves are a lighter green and maybe begining to turn yellow is this normal? are the dieing? any feedback will be helpfull im new to cloning so please help
the plants are under 4 cfl lights hanging about 8 inches above them
room temperature is at 75-80 day and night
humidity high is steady about 85%

You will see that happen in the 7-14 day period. It's usually a good thing, if the rest of the cutting is still vibrant and perky. It means the plant is using the nitrogen and other nutrients stored in the leaves to send out roots.

The goal is to have plants stay green and healthy the whole time.
Any other colors are bad things.
Purple stems can be from cold weather, phosphorous deficiency or genetics. Yellowing shows up when plants us up the nutrients they have stored in them.

The health of the stock plant is the most important factor. Take cuttings from healthy, thick growing tips. Try to avoid the little spindly guys at the bottom and the ragers at the top. Try not to shock the clones as you are taking themm spray the tray every 5-10 cuttings just to keep them moist.

Try to keep the root zone 10 degrees warmer than the shoots, without going out of bounds (80-70).