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Ok, I know after all this time I should know the answer to this but it's something that still confuses me.

I've searched different forums and read about basking temps. Many people say to keep the temp at about 28-30 degrees C, on the Dutch forums they say 30-35 degrees C.

On these forums I see a lot of people saying they are using 60 watt bulbs and when I look at the photos they are quite close to the basking areas.

When I use a 40 watt and put it at the same sort of distance I end up with temps of 40+ degrees C.

The thing I don't get is, when taking the temp of your basking area, do you take it in the hottest area directly under the light? When I place the end of my thermometer (the red area at the end of the glass thermometer) right under the hottest part it will (for example) 42 degrees. If I move it even the slightest bit to the side it will say a temp quite a bit less, like 30 degrees or something.

How are people using 60 watt bulbs at such short distances and still keeping such low temps? How do you measure the basking temp exactly? Is it because I'm using a glass thermometer that it seems so wonky for me?

I don't know if this completely answers your question...

I have a large dock and I make sure that the hottest spot is around 10 degrees warmer than my water. I let the rest of the dock vary and the turts choose where they are comfortable.

A few of us put something roughly the size of our turtles (like a rock) directly under the basking area and place the thermometer on top of that for a few minutes.

I was actually measuring the temps last night as I was cleaning the tank. If you place the thermometer vertically, you'd get the lowest temp and if it is placed horizontally, you'd get the highest temp.

In the end, I'd trust the highest temp reading at the correct height.

Are you using a spot or flood light? A spot light will concentrate the heat in a tighter area.
I use a small 40w halogen flood with a dimmer so I can adjust it. I use one of those cheap digital thermometers and I measure directly under it (90F). Some times my guys sit directly under it, stacked on top of each other, sometimes they all spread out and will have just their heads or butts directly under the warmest spot.....

I'm using a 40 watt spotlight.

Try switching the bulb to a flood if you can, it will spread the heat out a little more evenly.

Use whatever watt bulb at whatever distance that will make the basking area temp 88-90F.