I would go with the 2"-1/8" wall. Bigger tubing means less bracing and crossmembers and No second guessing "Is it strong enough" In all reality you know, strength structurally the smaller 1.5"-1/8" wall tubing with more bracing would be stronger than the bigger 2"-1/8" wall tubing with less bracing. Your trying to avoid alot of bracing so you can remove your sump and to do maintenance from the front or sides. Also I stress to you that steel and saltwater aren't best friends
![Grin ;D](https://ohioreef.com/Smileys/default/grin.gif)
, so If you plan on keeping this setup for years to come, get it powder coated from a local shop. It shouldn't be more than $75 bucks a would think because a quote on the Huge yellow hook was $30. I have a couple Painted steel crossmembers on the backside on my doors for my stand and after 4 years there rusted bad. Not just surface rust but pitted deep, I just sanded them down acouple days ago.
P.S Make the canopy out of the 2"-1/8" wall too...LOL