I would think if the UVB bulb is close enough it should be no problem. 10 is for a Larger/deeper enclosure where you need the extra UVB to reach to the bottom. Too much UVB is a problem in my opinion the Tort's eyes can suffer. I have seem the effects of too much UVB on my chameleon eyes.
As far...
I know its an old post. I had the same type bug so I thought I might tell my success story.
I used Dawn dish soap and water in a sprayer. Use 1-2% soap, remainder water.
Remove Water, food dish and tort.
Spray enclosure, Substrate bedding & Hide House. Spray your Plant Leaves above and under...