Early nutrients

What are people doing for nutrients in one of two situations:
Aero setup devoted to clones
Aero setup devoted to Seeds

It seems like many people here are using just water and a bit of indole butyric acid (from whatever company you prefer) but others may be using small amounts of nutrients.

What would you do if a seedling came up with slightly more yellow than green leaves?
Add a bit of nitrogen or nothing to avoid burning?

I've had clone in straight water from the day I took em to about 12 days. And I never give my seedlings anything but water until about the second maybe third set of true leaves and when they do get nutes it very light(200-300tds).

A seed contains everything the plant needs to get started.
Clones are up to your own methods.