When to clean your ATS screen

[leepink23]

I have read to clean your screen weekly but I recently had my tank fallow so the ATS wasn't producing much. It's now producing again and I wonder how often and how clean should I clean the screen.

 

[leepink23]

I have read to clean your screen weekly but I recently had my tank fallow so the ATS wasn't producing much. It's now producing again and I wonder how often and how clean should I clean the screen.

Image 1 and 3 are duplicate, image 2 is 1 week after image 1.