I just bought a 20 gallon tank, and I did everything right in setting it up aside from wiping down the aquarium before I put the water in. Now, my Oranda is swimming around in there, and I am worried about what might be lurking in those waters. Has anyone done this? Will the filter take care of this screw up? Also, I want him to have a friend, but I want him to have ample room. Is a 20 gallon too small for two Orandas?