I would like to propose a new community project or rather describe a project I intend to undertake and allow any and all that are interested participate in through species selection and other means. Every project needs a goal so I will state mine. To create a nearly self sustaining self contained Biotope type aquarium. The ecosystem I would like to replicate is the Caribbean. I do not want to preform frequent water treatments or changes. If possible I would like to eventually introduce at least one clown fish and one anemone. Current supplies and steps so far... I bought a 20 Gallon tank (I know this is less than half the recommended size for saltwater tanks the size of my house along with finances forced this constraint.) It came equipped with a standard 18" florescent overhead light and a power filter which circulates the water very well through two C size filters and two paddle wheel looking filters. (I am new to aquariums this is my first tank other than a brief adventure as a child, If someone becomes interested in this project and teaches me the nomenclature and jargon I will adjust my terminology accordingly.) I then sought the help of a seemingly reliable employee of a mall type pet store and bought 20lbs of "CaribSea" sand. (Google it if your interested in the microbial inhabitants I think its a nationwide brand) and a 10lb live rock according to the man at the pet-store this particular rock had been established in a Caribbean environment tank for over a year. (I do know he took it out of such a tank and that it is beautiful covered with at least 4 or 5 obviously different mosses and algae) and 5 more pounds of plain lace rock. last but not least the pet-store employee strongly suggested (to the point of giving it to me for free) that I introduce one freshwater molly he said it may even survive but its primary function is apparently to introduce additional ammonia. On the advice of the pet-store guy I replaced my light with a 20k light (he suggested a 50/50 light but they were out of stock and he said this would work (nearly as well) since my tank gets some indirect sunlight anyway. I finally bought a 50w tank heater (got it home and found that for a 10 degree change above room temperature in a 20 gallon tank 100w is recommended but I will add another heater later if needed) and a floating thermometer. So I came home and added 7.5 cups of salt to 15 gallons of distilled water stirred ... added the sand the rocks and my fish... this is day one.. I will soon have a test kit so I can monitor PH, Salinity and other chemical questions you may have. Challenges: Species Selection: It would seem to me the first question is species selection and introduction times. From what I have read and am beginning to understand is the first species introduced are invertebrates. Also I have learned that there several small invertebrate species probably already living in my sand. For the more visible ones... In my readings I have found a supposed rule of thumb that says you should have one invertebrate per gallon of water but others have said this is for very small specimens and will cause you to have to remove them overtime... So I am still unsure of population densities. One blogger who has a 20 gallon Caribbean tank (it was never disclosed how self sustaining his tank is suggests only 5 specimens) In any case for species of invertebrates I was considering Astrea Snails http://www.reefcorner.com/SpecimenSheets/astrea_snail.htm Hermit Crabs http://en.wikipedia.org/wiki/Caribbean_hermit_crab and possibly a Peppermint Shrimp. I would greatly appreciate any feedback suggestions or ideas that could add to the biodiversity or sustainability of this project. Are these decent species choices? How will I know when its time to introduce them?