Need advice on lights for seedlings indoors

Hi everybody, I am doing a grow indoors with 15 seeds in 15 Coir pots, 16cm diameter and 4 litre capacity.I will move pots to larger containers when stronger without transplanting.
I will start in a grow tent 120x60 cmx 160cm high.I figure my 250 wattHPS in a cold tube will be fine for the first few weeks. I am unsure how many lumens to give the seeds/seedlings. Some say 4000 is enough.Some say 14 inches height is about right.?
I would love any input from experienced growers.