With any new tank, you have to let it run for 24 hours.
(filter, airstones, heater running) This gets rid of
the 'new tank syndrome' that can make your fishy ill.
You can use water from the existing tank to help
jumpstart the cycle process. (see link) Another
thing that will help with cycling is to take the filter
cartridge from the running tank and either add to
the new filter or hang along the back of the tank,
or just move the whole filter onto the new tank if
room allows it. Basically anything that was in the
old tank can be moved into the new one. The good
bacteria will have attached to plants, gravel,
caves, air tubing you name it.
I think that all makes sense, it did typing it.
If not, ask about any part that was hazy.
http://www.kokosgoldfish.com/cycle.htmlBTW, how big is your existing tank? and the new one?