How Best to Increase Biodiversity?

As others have said a lot of diversity will hitchhike in. Corals add some, macro algae tends to add a lot, live sand from an established tank... A diverse set of organismes will undoubtably find its way in, the key really is keeping them alive. Planning strategically is important if this is the goal. Adding a wrasse, or starfish, or sandsifting goby for example, can really hinder the diversity thing.... Adding food sources can help. Phytoplankton for example trickles up the food web and can help keep things going. This is fairly easy. Dosing certain nutrients can also help, but can be more complicated. Nothing survives without food though.

 

Just make sure if you borrow rocks that you aren't getting aiptasia, majano, or other pest diversity!