Yipes...
Wait, wait wait.
Many sand "sifting" critters are not good overall for your tank and sand bed.
Imho, the greatest sandbed cleaners are the thousands of tiny micro critters that come in quality live sand; Pods, tiny stars, tons of worms, etc. all are great scavengers. Many sand "sifting" creatures eat these, sterilize your sand bed, then starve in your tank.
Cucumbers are good, but be careful. A Cucumber death can be very toxic to your tank.
A variety of snails make great janitors. Nass. snails stir the top layer of your sand bed (they burrow under the sand to hide and come out at night or when they smell food) and feed on scraps, Cerith and Turbo snails eat algae. So a variety work well.
Get some quality, fresh live sand (can buy it from here) or get a cupfull from an established, healthy reef tank to jump start your sand bed.
As your tank matures a Brittle Star (not green) makes a nice addition.
Hermits can be good, but they tend to kill your snails.