Hey Weez,
My light meter helps me quantify, but I never measured a light source for seeding/clone so I don't know what my target value is. I was thinking 1,000 to 3,000 lux? I don't think they want it too bright for new seedling clones, but I've been wrong before.

I tried searching for measured lighting levels on the net but I don't think I used the best terms for searching.

At about 3-4 " I can get about 23,000 lux but it does start to get warm.

Do I need to worry about TDS meter for DWC to measure nutrient strength, BTW>

M.P.