Good advice Giant.
Don,t worry about PH and fans etc.....
Your best bet is a flouresant , any will do but cool white is the boy.
It,s a weed and will grow easily without worrying too much about anything.
Use growbag soil for tomatoes and keep it just moist not wet with a flouresant a couple of inches away from the seedling, and keep the temp around 20-25oc and she,ll grow.
There is no point putting a 250 sodium on a seedling as due to very small leaves and very few of them they can,t photosynthasize very quickly , so keep it under a flouresant untill you got atleast 3 or 5 fingered leaves on it.