Brown Algae on Media

[Norbyland]

I have a newly (fish-in) cycled 13 gallon tank . I’ve noticed a little brown algae on the plants and the walls which I’m not too worried about. I have a bio sponge that the filter water flows through and it used to be bright blue. Please see the photo lol. It’s completely brown now. Should I replace it? The water levels are really good right now so I’m afraid to do anything

 

[Spudsssy]

Give it a good squeeze in tank water when doing water change (never tap water). You never need to replace bio sponge. All your beneficial bacteria lives in it.