Clean sand
 

My sand was always dirty, I mean you can see detritus settle on it even though I have many current. I bought a diamond watchman goby and did a good job but he cleaned the sand and covered the corals and rocks with sand so I had to remove him..

Is there a method or any other good fish / inverts that keep the sand clean without doing a mess like this goby did?

I use the typical stuff. Crabs and snails. I sand sifting star may work well. Good flow is the key to keeping waste suspended in water.

-=E=-

Try a fighting conch

what size tank and how many GPH do you turn over... alot of people say that have plenty of current until they have a problem.

In your sized tank a few generic sea cucumbers should make a noticable difference ... nothing fancy they actually look like turds but they will come out at night and scour the substrate for organic matter.