thanks!
Not sure if I want sand-sifting gobies.. I hear they make a mess of things. got to look more into them.
Blennies are nice to have, I'll add them to my list
If you need safer sand-sifter, get a Two Spot gobie (Signigobius biocellatus), they also sift whole day, but they are not burrowing and they don't rearrange. You have to have live sand and see it eating food at the store, they rarely eat frozen food and/or have to be spot fed. Often sold in pairs.
Other very peacefull small fish you might want to check: Pink-Streaked Wrasse - very small and shy, won't bother any fish, constantly cleans corals and rocks. I'd not get a Six-Line in the same tank, therre is a risk the SL would be aggressive against the pigmy wrasse.
Butterfly fish, but only if you can see it eating and you have ample space.
Also dragonettes, some of them are very small and quite entertaining. Often sold in pairs.
On a side note, be carefull with blennies, they have great personalities, but there are some that nip on other fish, and not all of them would touch algae. The Algae blenny (Salarias fasciatus) is widely popular algae cleaner, but most of the time it just starves in a tank, not enough algae for its body mass, it's one of the bigger blennies in the trade.
Tangs are great algae eaters, just not any algae. And they will also make smaller fish hide more, so it's a trade, you either get 2-3 of them (mind you, different types) so the small fish will get used to bigger stuff around, and risk tang wars, or just avoid having more than one risking some fish would be scared because of it's size. In a populated tank with corals it wouldn't matter that much as fish will see less of each other.