I have my 40b QT on this type of shelving and while you can do it, its not ideal for two reasons.
- The steel isnt covered in any significant coating and will rust almost immediately upon contact with salt water. Mine is rusting and pitting all around.
- The particle board shelves that come with these shelves arent made to get wet. When they do get wet, then the swell and start to fall apart.
That said, if this is something that you are wanting to do, there are a few things you can do to make it "more better"
- A quick spray coating of flex-seal or other spray on rubber/bed liner material can coat the steel frame and better protect it from water, so it doesnt rust.
- Check to make sure that your shelves have support for the shelf all the way around the frame. You can see the "divot" in my frame that is the push out for the shelf to rest on, this provides a static full steel support for the tank frame. Some of the cheaper shelving have little "fingers" that support the shelves, which will fail with the static load of a tank like this.
- Replace the particle board with something more rigid like painted/bed liner covered plywood. This will give you more stability overtime.
Ive been using this stand for my 40b for the better part of a year on and off (its a QT, so its not always full and running) without issue, but I made sure to address the weak points of the frame. Also, once you set this down, you CAN NOT move it. The steel frame will bend if you push/pull it with the tank on top of it, and once its compromised, you are hosed.