done all my research on these guys just a few questions that I haven't been able to find answers for my self those are 1) witch tank is better (measurements are in inches LxWxH) 36x18x18, 36x18x12, or 24x18x12. 2) how deep of a pond would be too deep? iam thinking 4-6" 3) are guppies ok in the pond? I understand they will get eaten that's one the reasons they will be in there and how about a pleco? 4) does anyone have any tips or hints for building a diy waterfall with a stream to the pond? Thanks in advance