Beginner needs your help

[mike31154]

Yeah baby, 210 gal, that's the way to start!! No kidding, with that amount of volume, it's less likely you will suffer any dire consequences if you make an error. From what I've heard, read, googled ... starting small, especially with SW is more difficult since a mistake can crash the system pretty quick ... more difficult to keep small systems stable than larger ones.
I started with a used 75 gal, bought another used 65 gal six months later and now have a new 90 gal sitting dry in the basement waiting to build. The used 75 or 65 will come in handy as a sump/refugium.