yes you can place the bio wheel in an existing tank.
also if you use sponges in the existing tank you can take squeezinx from the existing tank and seed the new tank.
just like using bio spira you seed the new tank with bacteria from an existing tank..you can also run a sponge filter in the existing tank..by christmas that will be loaded with bacteria
if you do this the cycle can take only 4-5 days.