I currently have a well cycled 10g tank and just got a new (well used actually) 37g tank that will need to be cycled. The cycled 10g currently has the following fish: -2 Platys -1 Dwarf Gourami -1 Rubber Lipped Pleco I want to keep the 10g tank set up - so this technically isnt an upgrade, but more of an addition. Here is what I am thinking of doing. Please let me know if this will work. 1. Get the 37g tank all set up with water and filter (Marineland Penguin 200) 2. Move the 2 Platys from the 10g tank to the 37g tank 2. Take the Aqualand 5-10 filter media out of the 10g tank and place it in the filter box of the Penguin 200 in the 37g tank 4. Replace the Aqualand 5-10 filter media with a new cartridge 5. Wait for a couple of days and if ammonia and nitrite are under control in the 37g tank, go ahead and move the remaining fish to the 37g tank. My assumptions are: 1. There will be enough bacteria in the ornaments and substrate of the 10g tank to support a filter media swap (old for new) 2. The old filter media from the 10g tank will be sufficient to help "seed" the bacteria in the new 37g tank. What do you guys think?