Thanks for all the compliments
In the next few months I think he'll be ready for a tank upgrade. He's in a 180 gallon now. I had him in a custom 300 that was 72x60x 20. It was so massive he was scared and not active. I tried about 15 different light/decor options in that tank and couldn't find a way to make him feel secure. Once I downgraded him to a 180 gallon it was night and day difference. He wanted to eat more, be more active etc. I'm looking around for a 36 inch front to back deep tank for the next step. I want to avoid putting him in the larger custom tank as I don't think he's ready for it yet.
I think one of the keys to my success is keeping a goldfish and bristlenose with him to help digest his poop. I've kept tetras, rainbows, corys etc with him in the past, but none of them loved to help clean as much as a common goldfish. I believe that there is a lot of undigested nutrients in the MBU's poop from it being so large and them working through it so fast.
I water change every 3-4 weeks at about 65% of the water volume. 180 gallon + 40 gallon sump. I'm changing like 150 gallons of water at a time. Nitrates never seem to get very high, nor do the TDS. But when the sump starts making noise from splashing into the filter socks, it's time to add water, so I just do a large water change anyways.