The ultimate weight "challenge" was to fill the Aeration Bench (without holes) with water, trying to collapse the Bench support assembly. As a worst-case test, I did NOT attach the two bolts that secure the upper portion of the Aeration Bench to the outer container. I then applied a maximum dead weight load by filling the Aeration Bench to the brim with water. Fully loaded, it held 21 gallons. This equates to a mass of 175 pounds sitting soley on the bench assembly:

To be expected, the sides of both (unsecured) containers flared out. But now after 10 hours the bench assembly is holding fast.

Next, I built a second 'Tainer but this time, securing the two containers with the two upper bolts as per the Guide:

Upon filling with 21 gallons of water, notice there is much less flaring of the sidewalls, as compared with the unbolted set:

I plan to let these two 'Tainers sit as is for the next 7 days to fully evaluate the strength of the bench support assembly with this load. Of course, in real use with Potting Mix loaded, I am calculating a typical load factor of approx. 80 pounds, figuring in the (light) weight of the Bark fines plus Perlite. So, as of tonight I am pleased with the structural rigidity of the EarthTainer III design.

Raybo

In removing the unbolted Aeration Bench to look for any deformities in the support assembly, it looked as new:

Even examining the bolt holes themselves where stress would have occurred, everything looks fine:

So, my conclusion is that securing the Aeration Bench to the outer container with just the two upper bolts as in the current Guide is more than sufficient.

Raybo