The one thing I would do differently is?

[untamed]

I wish I had put a liftable subfloor into my fish room to make it easier to put things into spots they weren't planned for. I'm now realizing that my plan wasn't "perfect" (ha...there's a surprise!!), but it is really hard to modify things after the fact.

I didn't plan for a refugium and managed to squeeze that in. Now, I'm trying to figure out how to install a larger skimmer....ozone...UV...

I suppose there just wasn't enough flexibility in the plan... Now that it is running, every mod is much harder.