I have gotten this question from one of our readers: How to grow xmas moss in high temperature? I think it is the common interest of many people out there, so let me quickly put down a few points to address the question:

1. First of all, expect a slower growth rate of the moss (many other experts are stressing the importance of low temperature - and I do agree) - but it is not impossible to grow them in your aquarium tank, but just to expect slower growth from the aquatic moss.

2. Fix one to two extra 12V fan (those that you could find in the computer casing / chasis). You could fix the fan(s) to a large plastic clip, which you can easily clip it onto the edge of the aquarium tank.
- Make it blowing at a 45 degree onto the tank surface. It increases the water evaporation rate - and when the water atoms transform from liquid into gas - it brings away energy (in another word - heat). So, the temperature will drop at least 1 degree C.

3. Tie the moss onto driftwood or wire mesh. For some unknown reasons (perhaps the moss absorb nutrient better from those substances trapped in the wood/mesh), the aquatic moss (including xmas moss) grows faster, which could offset the slow growth rate from the higher temperature

4. Keep the xmas moss closer to the surface. I notice it with one of the tanks - that the xmas moss grow exceptionally well when I have lesser water in the tank. You could try it as well.
That’s all. All the best!

David