If you use two aquariums, one will serve as a control for the demonstration. Obtain live oysters from a local seafood market or grocer. If you do not have access to a body of water that supports oysters, you may use stream or dechlorinated tap water mixed with sea salt to the correct salinity for oysters. Oysters can survive in salinities ranging from 12 ppt. Add at least 12 ml of salt for every liter of water in the aquarium.
Sea salt is available at most pet and aquarium supply stores.
Allow your oysters to acclimate to the aquarium for 24 hours so that they will be ready to filter when you do your demonstration. Oysters can be temperamental when they have been out of their natural habitat for some time. If you plan to keep your oysters in the aquarium for more than a day or so, you should set up a bubbler system to oxygenate the water and a filter to get rid of toxic ammonia. Since oysters require massive amounts of algae to survive, we suggest that you do not keep them long, unless you feed them with algae paste. Oysters can filter sediments and algae that are suspended in the water, but they will not filter sand or clay.