Rock and sand and anything dead/dying/rotting in there will smell like that. Whenever you move stuff around in your tank, you are going to release crap into the water column. That crap is going to smell like...crap. :)
Get yourself a brittlestar and put in your tank, I have one in mine, when I move a rock its clean as a whistle underneath, those babies are worth thier weight in gold as far as keeping hard to reach areas clean! I would not be without one!! Got mine at LFS for about 12 $
Around six inches, I have a 34 callon RedSea Max my brittle does just fine in mine, yours will be just fine with a brittle star don't get a green one, they eat fish, I have a Brownish red one, I got it at Petco
If you get onedrip acclimate it a good 3 hours What I did was let it drip until there was double the water, pour half out and drip till it was double water amt again dump half and drip again till double, don't expose it to air, scoop it back into the bag with water from your bucket and dump in the aquarium, he will make himself right at home and keep your sand nice and clean:)specially under and behind rocks
My local saltwater guy at lfs suggested due to me not having any livestock i leave my lights off for a week to clean up algae in my tank. I took it a step further and took a black trash bag and covered the glass and even turned off my moon lights. Any thoughts on this?
Yes, doing a black out will help with algae. But you have to be sure to do a large water change (~30%) when it is done. The algae will die off due to lack of light, but in doing so, it will release all its nutrients back into the water.