20 gal long , skimmer needed

[ElvisReef]

What’s a good skimmer for a 20 gal long , never needed one but anemones mushroom everything splitting and it seems like there’s floating shhi in tank

 

[ElvisReef]

Also , I need to figure out why so much is detritus or black stringy poop , when u blow it with a baster itll blow away but it make them look like poop in a day or 2

 

[ElvisReef]

Could my fluval fx4 have poor suction?

Would poor suction cause poor output ? Because it seems like output is good no issues on that side