50 gallons is much too small for anything but a new hatchling.
What wattage you need depends on many factors. I usually use 65 watt incandescent flood bulbs for heat and light, and a long florescent tube for UV. Or you could use a 100 watt MVB for heat light and UV all in one. Set it on a timer, and set the height of the fixture for the correct basking temp, and that is all a russian needs. Which UV bulb you use also depends on several factors, but I recommend that you do not use the coil types. Unless your house regularly drops below 55 at night, you shouldn't need night heat for a russian.