Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
1) Skim the top layer of old substrate. Put this in 3-4 mesh bags. Move the fish, filter, plants... everything into the new tank with the rest of the old substrate. That gets them out of the leaking tank. Hang the mesh bags in the tank where there is good water movement. These bags hold the substrate that has the most nitrifying bacteria. Remove one bag per week.
2) Put the new substrate into a bucket or something and keep doing water changes until the ammonia is gone. This can take over a month. Do lots of water changes. You do not have to worry about nitrogen cycling this substrate, the established filter is already cycled, and you are keeping it with the fish.
3) Fix the leak.
4) When the new substrate is ready (no more ammonia leaching) move everything back to the old tank. Skim the upper layer of the old substrate again, a reasonable population of bacteria has grown on it. Keep that in 3-4 mesh bags. Remove the remaining old substrate, put it in a bucket or whatever. You can use it in another tank, if you want.
5) Put the new substrate in the new tank, decorate, plant... then fill slowly with water. Pour the water in onto a plate or plastic bag. Let the water seep slowly over the edge of the plate and into the substrate. This will minimize clouding. Add equipment, mesh bags with the old substrate. Add fish.
Moving the substrate might kick up some ammonia. If you want to, you can spread out part 5) So you set up the tank one day then monitor it for a few days while the fish are still safe in the tank with their bacteria-rich filter.
6) Monitor the conditions in the new set up. Be ready to so some water changes if needed.