I also have a Rhinox diffuser and I really like it!
Some days ago I soaked mine in a 2% "klorin" (probobly not the english word ) solution diluted with destillated water for 24 hours. After that time the diffuser was cleaner than when I bought it!
After soaking in klorin i washed carefully with water and I also soaked it in destilled water for some hours before putting it to the tank again. It worked very well. I already see it begin to come even more algea of the glass diffuser