I have a 2.5 gallon mini bow with a 10 watt light.
The majority of the tank looks okay. There doesn't seem to be much algae until I looked at the filter. The filter pad is completely covered in what appears to be three or four different types of algae. I can't even see the filter itself.
What is the best way of dealing with this? Just chuck the pad and replace it? I just ordered a replacement but it will take a few days to come.
The filter is in direct line of the light so how can I stop this from happening again.
This is precisely why it seems designers never use the products they design. The light does hang over the filter pad and the algae IMO will always grow there (nutrients+light-plants=algae)
The problem with throwing out the filter material is that you are removing the bacteria that process aquarium waste.
We got rid of this little aquarium rather quickly because of this issue (as many others did with Fluval Chi. The only thing I can think of is to remove the filter itself and find a small internal filter for the tank.