I know at premium aquatics you can order inverts individually. I would suggest not mixing hermits as it can lead to missing hermits. I personally like the redlegs, they aren't much to look at but they really do a good job cleaning algae from rocks. I have about 50 or so in my 75 and you can see them crowding rocks with any algae and picking them dry. I have had nerites, turbos, nassarius, etc. I would probably start with around 20 or so algae eating snails to see how fast they go through the algae you have and add more if they are unable to keep up with it, too many times a large amount of these guys are added and they starve once their food supply is used up. Nassarius are good for stirring your sand bed, I might add about 10-20 or so of these guys. The sand star somewhat serves the same purpose, but I'm weary of stars as they can eat things you don't want them too. And the anemone crab is fun to watch, but is a filter feeder, therefore he would be much more of an aesthetic addition than a cleaner addition. Pods are always beneficial so I'd definately suggest getting a good population of those going in your fuge. Hope this helps.