Originally Posted by Apos
No snail I've ever had has gone down into the substrate: they stick to the LR and glass, end of story.
I'm actually kind of frustrated with the issue. The problem I seem to find from reading about each is that most things that eat out of the sand end up eating pretty much everything living in there, and if your tank isn't big enough or you don't have a very solid refugium, there's just not enough time to respawn before the creature dies.
Sand-sifting fish: most will starve to death unless you carefully train them to take supplemental food... in which case they do less sand-sifting
Sand sifting starfish: these starve to death, and fast, because they vacuum up everything living in your substrate in a matter of days. Pretty much a death sentence for the poor guys unless you have a TON of substrate and a refugium.
Cukes: ideal if you can find the right species to survive on what's in your tank, but almost all are still risky as far as causing a cuke nuke (i.e. they get scared, eject their innards, and kill everything in tank)
Seahares: often quietly starve to death
Urchins: pretty good, but can get stuck easily in heavy LR tanks, and often knock live rock around
There doesn't really seem to be a perfect solution. If snails, conches cowries and ablalones would actually go into the substrate and eat, that would be perfect, but often they won't, particularly if you have a gravelly/corally bed (like I do). The glass and LR is just too tempting to them, too easy.
Nassarius snails go down in the substrate, end of story.