Keeping shrimp can pose a problem when choosing the filtration for your aquarium. As most people keeping shrimp intend to try to breed them, it is necessary to choose a filtration method that will not harm the shrimp juveniles. Some shrimp can also be harmed as adults by strong currents created by filters.
A safe filter to use is the primitive air-driven sponge filter. This is my favourite method of filtration.
Here is your typical example. A tube from an air pump is connected to the base of the ‘funnel’. When the air pump is turned on, air begins to bubble up the funnel, causing water to flow up with it. Water is drawn into the funnel via one or more inlet funnels. These are covered by sponges, which act as a surface for nitrifying bacteria to inhabit. As the water flows through the sponge, the bacteria converts harmful ammonia into harmless compounds (see ‘nitrogen cycle’ for more details).
Other filters such as external canisters and internal power-head filters can be modified for shrimp. Covering the inlet pipe of an external filter makes sure small shrimp can not be sucked in. A spray-bar can also be added to the outlet pipe to ensure a strong current isn’t created. A strip of sponge can be wrapped around the inlet slits of internal power filters.
Another option is the controversial under-gravel filter. I personally find these systems problematic and often have problems in the aquaria I use them with. An under-gravel filter consists of a panel at the base of the tank and a funnel connected to it. An air stone connected to an air pump is placed at the bottom of the funnel. Water is drawn through the funnel and thus through the substrate of the aquarium. It is the substrate that acts as the surface for nitrifying bacteria.
An interesting method is to connect the funnel to the outlet pipe of an external canister filter. The water then flows up through the substrate rather than down it, preventing clogging of debris in the panels.
I will type up filter information in a more structured way when I have time… It’s hard to organise a post when there are so many methods to talk about, such as…
Internal: Air-driven sponge, sponge power-head, under-gravel, internal canister, Hamburger mattenfilter.
External: External canisters, waterfall.