My intention was to build a controller so I coulf vary the ratio of blue to green light but at the moment I just have a rotary switch which gives the options of red only, redd, green and blue (white), blue only, green only and blue and green together.

I have not tried filters but I do have plans to make a new light source with some very bright white LEDs I have at work. I think filters will work with them.

Mine does not have a tray for filters.