Change the Filter or is it ok?

[IHaveANewHobby:)]

Hello Everyone!
I did a 50% water chage on Friday and today I checked my water parameters. All is good. I still have just my two danios, and wanted to add a few more later on this week.

Question:
My filter gets rinsed in old filter water every water change, however this time I pulled it out and it was green in color.
Is this good? Should I change the filter, being that I want to get new fish? or should I leave the filter? I have 0 blockage. Flows just nicely

 

[n00dle]

probly just algie

 

[IHaveANewHobby:)]

Thats what I figure too, but how long is too long to keep a filter cartrige in a 25 gallon (US) tank? BTW it is a Whisper Filter.

 

[n00dle]

iam not sure m8 i just clean mine every saturday ive had mine in there for ages and its second hand tank