Bacteria of the sorts which break down ammonia, nitrites and nitrates live on the sides and "structure" in a tank. I have a set-up tank from which I start new tanks. Not only water is added to the new tank, but also a layer of gravel, if possible a ripe filter as has been suggested and as many plants as can be spared. Don't have driftwood or rocks to spare. Everything is moved wet.
The more you can clone a tank from another, the better. Soon after that tank is set up, it would be good to introduce the fish or the bacteria, which have been processing waste products, may otherwise decline in numbers from starvation.
Faster growing plants such as water sprite, hornwort, the "bunch plants" and Najas (hated by the aquatic gardeners because it grows too fast) are useful. The plants, in that they use nitrogen, don't really encourage the development of the nitrogen cycle, but they are comforting for the fish and may help the tank over rough spots when substances spike. Your rainbows will thank you. :)
All the best!
Scott (not a chemist) Davis
I run an extra sponge filter in a tank so if/when I need to setup an extra tank in a hurry it is ready to go.
Pete
--- In r_m_l at yahoogroups.com, Gary Lange <rainbowfish4u2 at y...> wrote:
>
> I think everybodys got it right you're just seeing it from a few
different angles...