I'm new but i know there is a few cucumbers that sift the sand and also the more snails and small hermits you have the more effect you will see in your tank. My friend has tons, maybe around 300, of snails and crabs of assorted nature. but yeah there are also gobies but im not sure if you have to have you tnak set up for a while... i know you have to have at least 1yr into it to add a mandarin. however their are certain blennys that will do about the same, such as the sailfin blenny aka lawnmower blenny. The only thing is that they may act agressive toward other blennys so be careful if you add more then one. Also with the cucumbers, you have to take good care of them and watch them cuz if they die they will release a toxin in your tank.