The perfect FOWLR

[Myka]

I am thinking of setting up a decent sized FOWLR for large Angels and Butterflies mainly. Keeping this in mind, what do you think would be the perfect 6' or 8' tank with max width of 20"? I'm thinking 96x20x28" or 72x18x24". Obviously the 6' tank would be much cheaper since it is a standard size, but I would have to be careful about selecting the smaller large Angels if I chose a smaller tank. I don't have my heart set on any of the huge Angels like the Queen though, so that could be my saving grace!