Very good idea to use the existing water. Will you be tearing down the 10 gallon then? Also, will be using a new filter or can you use the existing filter from the 10 gallon? If you're using the same type of substrate, take a few handfuls from the 10 gallon, without disturbing it too much, and place it in the 20. That will transfer a lot of bacteria. If you're using different substrate, you can place a few handfuls of substrate into a flat piece of tupperware and put it in the 20 for a while. That will speed up the cycle. So will using the existing filter, without cleaning it of course.

Z

You could also add one of the commercial bacteria products and your 20 long should cycle very quickly. All of that plus the bacteria product is how I cycled mine in 10 days without fish.

Z

I have had the best success with Nutrafin's bacteria product. Many of these bacterial products have a shelf life and are useless after sitting for a while. Nutrafin's product is good for 2-3 years, and I used it to fishlessly cycle my most recent two tanks.

Zambize

The twenty will have two twenty gallon whisper filters, I change about 10-15% of the water in all my tanks every 4 or 5 days. I am now considering putting this setup in my thirty and moving my goldies to the twenty and keep the ten how it is. Im sticking with the Gourami, Tetras, and Corys in the thirty. Another question, in a thirty with plenty of vegitation and a floating plant, would I be able to keep more than one dwarf gourami?oh and before its asked, the thirty has a whisper 30-60 and a whisper 10 filters.

tiger get a salt tank :))