[Dolf]

I would not add a lot of anything to begin with. My advice (and there are those who will disagree) is to stay clear of crabs. They are omnivores and will one day start getting a taste for meat. Emeralds are often sold as a “good” crab, but I have pictures of my emerald pulling a hermit out of it’s shell and snacking- no, the hermit was not dead to begin with. I have since sworn off of hermits, emeralds and all other crabs.

Without knowing your setup and what you want to keep it is a difficult question to answer. If you have some sand in the bottom I would add a couple of nassarius snails to keep the sand turning a little and they eat anything dead (though they don’t really “do” algae.) Remember to feed them even if you have nothing else in the tank. A piece of shrimp occasionally will do.

I would add a few snails to control algae- not too many even in the case of an outbreak. The algae will eventually disappear once the nutrients are used and you will end up with dead snails. Being as you asked “how many” I suppose I would start with 3 or 4 when you can actually SEE algae and add a few more as the algae grow (again, no point is starving the little buggers- they are expensive.) Also, your tank will likely grow different types of algae as it matures and adding a species to take care of a problem that will go away on it’s own does not make sense.

Now, you can add some shrimp or not as you see fit. Shrimp will “pick” at smaller life that will otherwise help clean up your tank, but they also pick at the leftovers. Again, a personal choice on how you want to keep your tank. Personally I prefer to have worms and bugs eat the leftovers and keep shrimp away (and, as this is how I keep a tank it must be “right…”)

Well, you are on the right track. Keep researching and asking questions- but again I come back to the point that it is all dependant on how you want to keep your tank and the trade-off’s that you will put up with for what you do or do not add. Best of luck…