Thanks, I am glad to hear you like my set up. I work for a mechanical contractor and we use unistrut on projects all the time. I had all wooden stands and while they work well, they don't last forever, and after time they just look bad. I wanted to go with metal stands but I didn't want to pay a welder and have them eventually rust. Unistrut is an extruded metal, hot dipped galvanized and comes with assorted fittings so you can bolt your stands together. Since I live in an earthquake zone, I got a seismic engineer to help me design them. One drawback is going to be the length you can span this product, it will depend on your weight. The majority of my spans are 4', so if you have a large long tank, it requires some math, to figure out if you can go longer. Unistrut is a brand name, there are many other different manufacturers; bee-line tolstrut, etc. I took about 3 years to change out all my stands, it was quite a project. At the time steel was a little cheaper or the same amount as wood, but since then steel has gone up, and now it is quite a bit more expensive then wood, but it should last forever. This product is at some Home Depot type stores, and at any plumbing supply house.
You may want to check out metal stands that are used at places like Costco, and I have also heard of people using metal stands bought at home depot that are rated for higher weights. These types of stands are less cost, if you can work around the sizes. I found that I would end up cutting and changing the pre-fab stands so much, that it really wasn't worth it.
A fish room is always a work in progress!