12-13" away from a Russian hatchling. I haven't gotten her yet, weather is too cold to ship. Just want to work out little details now to make sure it's ready for her.
I don't know squat about Russians but I would think they need more UVB than a tropical tort like a Redfoot. If the UVB results listed above by Tom are correct the bulb you are getting puts out about 1.0 and your 12" is at the manufacturer max distance so your tort would probably get less than that. A box turtle like mine can get what it needs from that but I don't know about Russians needs. My gut feeling is that is not enough UV for them. A high output bulb will give you more like 2.5 on the UVB scale. Just remember that if you get a HO bulb that you need a HO fixture.