Distance of mvb to basking spot?

[mini_max]

I recently purchased a new mvb. I decided to down the wattage to 100, but I'm finding I have to lower the fixture to achieve the right basking temp. How close is too close? His bulb is sitting about 12" from the substrate. I am concerned because I'm noticing some pinky marks on his head...they could be staining from the radicchio he's been eating, but I'm worried it could be like a sunburn?

 

[Tom]

I use my thermometer to set the height of my MVBs.

I've never had any issues with "sunburn" this way.

Its always best to use a UV meter to check these things. I like this one: https://www.solarmeter.com/model65.html

 

[mini_max]

Thanks. I base my height on temp readings too. Until I get my hands on a uv meter, does a foot sound like an inappropriate distance? I know you can't know for sure, but based on experience, is it unheard of? I'm fairly new to mvbs. My last one was a much higher wattage, so it was mounted much higher, and I didn't have to even think about it.

I'm just trying to judge whether I should get a new bulb, I don't have much longer to return this one.

 

[Careym13]

Usually the manufacturer of the bulb will provide recommendations on how high the bulb should be mounted. 12" shouldn't normally be an issue. My MVB is 14" off of the substrate and about 12" above carapace height.