I just use a 20 gallon tank with 2" of water in the bottom and three aquarium filters that suck up the water and pour it back out simulating rain. I removed the actual filter part of them though so I'm really just using the units for stimulation purposes. I have a small portion of the tank that has large smooth pebbles piled together so they can get mostly out of the water. I also put the under tank heating pad on the side of the tank because the water tends to get a little to hot if under it. Before you go through this, you will need to put them through a cool dry season "winter" for a couple of months. Make sure that they don't dry out to the point of being in danger of dehydration. And cool means 70F. very little food if any should be given to them. I still keep them in separate tanks during the "winter" cause they have tried to eat each other before! After this stage, return them to their normal climate and feed them well for a couple of days. Then put them in the rain chamber and monitor them closely making sure they are breeding not cannibalizing. if you are not watching them then I would separate them.