to start off with i suggest getting like 10 to 15 small hermits such as scarlet hermits, zebra hermits, or blueleg hermits (all shouldnt get above an inch in size) i have scarlet hermits whic do a good job
then for algea i suggest a few mexican turbo snails. and then like 10 Nassarius snails.
and then for cleaning up food and other particles probaly a arrow crab or a aally lightfoot crab. both will be constantlty picking around eating algea and fod particles and a good treat for them is a whole pellet.
u should wait a month after tank is cycled to add them to make sure all conditions are stable for them cause they are not hardy creatures