170 ft. Galvanized Tension Wire

I use this product for a completely different item. The only thing I could suggest would be to go on Utube maybe you can find a video there. Please make sure you call and complain to a home depot regional manager. Putting up a fence should include the tension wire. That is just not right.

I naught what I was told to buy by the contractor

Soil - this wire would not be able to be used for greenhouse hoops. Thank you for asking.

I know right? I could bend 12.5ga. all day long. But 9ga.? It just about wore me down to a nub after only 3 hours. And I'm no weakling by any sense of the word. I also have gone through the revolving door of confusion but didn't get anywhere.

I would think so, depending on how tight it is tensioned, but that also requires some stout pole tie-offs at both ends, and I'd still expect some sag.

If you already have this item's wire loop, then, I suppose, you could cut 5 ft or so lengths and string them vertically (i.e., up and down; doing so horizontally (across) may cause the wire to drop down due to gravity, wind, rain, snow, being touched, etc), but, that would require something to attach this wire at the bottom, which I do not see in your photo. Most hardware stores carry rolls of light fencing/chicken wire - - both plastic and metal - - that would be perfect for the gap, and would be much easier to work with than this wire (n.b., if this is meant to be a long-term solution, I strongly recommend using metal fencing/chicken wire).

Oh I'm certain it will support 500 lbs. How you secure the intersections will determine if your grid will. If you're not making tight turns with this wire, you should be fine.

I do not believe this comes in any color other than silver/chrome, but, it can be painted. Make sure to use an enamel spray paint specifically for metal. However, weathering will erode the paint over time, so, be prepared to do touch-up work (I suggest doing this when the forecast calls for at least two straight days of no precipitation, to give the paint adequate time to dry/cure).

If you don't secure it at least every post, it may be tensioned but it will say. This wire is a lot tougher to work with than what you think. Make sure you have the proper tools and PPE.

Instead of welding, try putting a turnbuckle in the middle, so you can tighten it up when and if it becomes loose.