Easy To Read Thermometer

I use a basic, cheap, thermometer, the kind with a sucker to hold it onto the glass. But I also have a magnifying glass which makes it much easier to read. The main problem with this type of thermometer is that the suckers stop working and the thermometer drifts round with the water flow. I have lots of wood in my tanks so I try to use a bit of wood to wedge the thermometer in position.