Hey, I would look at getting some regular astrea snails, maybe some nassarius or whatever. I hear people mentioning those a lot. I was a big fan of the large trochus snails, but they always seem to fall on their back and die. I ordered 20 of them from here and none are alive anymore. However, all my astrea snails are working hard and living.
I'd say your clean up crew depends on your feeding, detritus, and algae issues. I like to use the recommended invert per gallon scale as a reference. But, I think if you don't have enough food, detritus, and algae, etc, that you can starve the inverts that feed.
Keep in mind this is just a culmination of what works for me, advice, and what I hear.
Your tank is just big enough for a fighting conch. I don't know about two, but one would work I feel. They are aggressive detritus and algae feeders on the sand bed. That's where they stay. But, since they are such aggressive feeders they can starve easily.
I would stick with scarlett, red legged hermits instead of others. They are the more passive, peaceful hermits yet they are aggressive detritus and algae eaters also. Mine are always scurrying around the tank cleaning up. I would say for your tank, with the conch, you could throw in 10-15 maybe.
Astrea snails... man you can probably throw in about 20 or so of them no problem in your tank. Im sure you know what they do.
Now, it's tough because I am just kind of speculating here. I have soooo many of these things in my tank. But it's a pretty large tank and I have some clean up issues. But, I hope this helps. Its a start. Let me know if I can offer more. Some other folks might be able to help. Plus, if they agree/disagree on what Ive said, it might offer a base of info.
