29 Gallon Tank Sponge filter cleaning question

Hi I have a 29g tank that I’ve had up for like 3-4ish months, I do water changes like 20-40% of the water every two weeks, I don’t think it’s overstocked, I have -a pair of honey gourami -7 Kuhli loaches -7 Pearl danios and two Cherry shrimp, I have a sponge filter going in there (it’s rated for 40g) every time I do a water change I squeeze out the filter sponge in some of the taken out tank water and it’s always super dark I guess the buckets kinda small like maybe a gallon (pictures below) is this a normal amount of dark or should I clean it more often? Thanks : )

 

Sponge filters get pretty gross. During a water change is plenty.

 

Hi, water quality is always harder to keep good in a smaller tank than larger ones, if I were you I'd go for weekly water changes rather than fortnightly of 30% , that water does look pretty manky, one thought though, do you have bogwood or anything that colours the water in your tank?

 

Hi, water quality is always harder to keep good in a smaller tank than larger ones, if I were you I'd go for weekly water changes rather than fortnightly of 30% , that water does look pretty manky, one thought though, do you have bogwood or anything that colours the water in your tank?

I do have driftwood in my tank, and there are a biiiit of tannins

Sponge filters get pretty gross. During a water change is plenty.

thanks, ill probably stick to that

 

I missed the every two weeks. Weekly will help for sure.

 

I missed the every two weeks. Weekly will help for sure.

Ok, I’ll try to do more