Tank is crashing :(

[iceman86]

Got home last night and went to the basement where my tank is and it smelled terrible like something was rotting and sure enough it was coming from the tank. Im guessing hydrogen sulphide releasing from the sand bed. My sandbed is only 2" thick but its really coarse sand and easy for detritus to trap itself in there. All fish and inverts are alive. The glass was also covered in green dust algae.

I'm guessing the sand bed needs replacing? I poked a couple spot and detritus like dust come out. I know it's normal to have a little but this seems more than I've ever had in my years of reefing.