Walls – What do I need for a wall shelf that will support an aquarium

A swiveling or articulating TV mount will tend to want to pull itself out of the wall when swiveled or extended, more than a flush-mount bracket would. Therefore, this situation calls for a bit of over-building to ensure safety, and to put up with the additional stresses of moving the bracket around.

You will need the following:

• A sheet of 3/4 inch plywood, cut as wide as the gap between the studs, plus at least 3.5 inches. It should be at least 50% taller than the mounting bracket. Hardware stores sell cut pieces of plywood that are 2 foot by 4 foot, so this is an easy choice as it requires only one cut if you don't mine the plywood being a bit over-sized.
• 6 qty of 3.5 or 4 inch lag bolts, or a box of 4 inch deck screws.
• 6 or more 1 inch bolts as fat as possible that fit through the mounting slots on the bracket, plus matching t-nuts and washers.

I suggest you pre-paint the plywood to match the wall or the bracket. Either will minimize the appearance of the plywood.

Center the bracket on the plywood and mark the holes. Drill holes big enough for the t-nuts and install them on the back side. Hang the plywood on the wall and mount it with the lag bolts or the deck screws. If you are using lag bolts, make sure to pre-drill the studs before installing the lag bolts. Since I can install a screw with one hand, I often use 2 deck screws to initially hang the plywood on the wall, then drill and install the lag bolts.

If you use only deck screws, try to find ones marked with a shear force rating and over build by a factor of 2-4. Or just install at least 6 or more per stud to be safe.

Non-load bearing means that it doesn't have the weight of the roof and ceiling bearing on it, basically, it can be removed with no ill effects. This has no bearing whatsoever on its capacity to hold a load, which has more to do with how the wall is tied in with the floor and roof joists. If you had a modern home I wouldn't worry about it. Since your home is (probably) not up to modern building codes you could have a professional mount it and thus bear any liability for the failure of the wall. If that isn't an option, inspect the condition and spacing of your studs and the anchoring of the wall into the floor and ceiling.