wow after reading this, a few other things around the site, and looking a few things up, I kinda feel bad about my guy Popeye, but I will say this: About 3 years ago I upgraded his tank from a 55 gallon with HOB Emperor filter to a tank I bought on craigslist, listed as a 150 gallon tank. I believe now that one of two things is true... either the filter I have is inadequate for the tank size (it's a Fluval 405), or the tank is actually a 100 gallon tank. The tank is waiting for me to move it out of my ex's house so I can't measure it this moment, but I will do so now. At any rate, the Fluval 405 has worked remarkably well for the years I've had it, especially as it was used when I got it. Nothing has broken, it doesn't leak, it circulates water with a heavy biological load, and it's quiet.
I apologize for the portions of this post that could be construed as "off-topic."