Bucket Filter...how often to change filter material?

[pfd161]

I have carbon in the bottom and pillow filler in the rest of my bucket filter running into a tank...wondering how often I need to change out the filter material?
Only have about 4 dozen shiners in there right now and the water has been ok but just worried about it...and ammonia.

anything else i should be using in this filter?

thanks!

Dennis

[gulp]

You did not say how big your tank is. How often you need to change is dependent on how many minnows and how much water.