If your tank has been running for a couple of months you can add a small set of cleaner crew animals. If you add them before you have a problem that may be able to keep the algae and detritus under control. Don't get the full pre-built packages with hundreds of animals for a 55 gallon tank. It too many, especially for someone with a clean tank.
Most people wait until they have a problem and then have to buy a lot more animals to fix their problem. Then, once the problem is fixed, they have way too many.
I added a small, basic cleaner crew as soon as my cylce was complete. A few red and blue leg hermits and a few turbo snails. From then on I added as necessary. I don't agree with adding a huge crew to a tank, rather get a species to solve a particular problem. If you have a buildup of detritus get a sea cucumber or a sifting goby. If you've got a lot of algae on the glass, get some turbo snails. Bubble algae get an emerald crab. This will stop you from having critters die of starvation. With the right balance of fish and inverts you should have few problems. When I feed my tank, some food reaches the bottom for the hermits and starfish. My cleaner shrimp and coral banded will eat up the big bits. The sea cucumber, goby and small starfish take care of the detritus and the snails take care of the algae on the glass. Everyone gets fed and there is little waste leftover to rot.
If you algae starting to grow, go ahead and get some turbo snails and blue leg hermits. (I bought my tank with large hermits that were a menace to snails, etc.) If you have a sand bottom, then narcissus snails are good too.
Just be careful to not buy to many unless you have the growth to support them. It's easy to busy too many and then end up with starving animals.