Don't dismiss the mineralized topsoil idea, just because you don't have the listed ingredients. The idea is good anyway, and is more flexible that you would expect from reading that sticky. All you are trying to do is convert any ammonia compounds in the topsoil to nitrate compounds. You do that by repeated soaking and drying of the topsoil. Once you have done that for a few cycles, you can use the topsoil, covered with an inch or so of pool filter sand. If you want to try to come close to the recipe in the sticky, look for other calcium carbonate forms, like cuttlebone (sold for birds) or crushed coral, or crushed limestone. All you need is a dusting of the bottom of the tank, not much at all. For the muriate of potash, I suggest just ignoring that part. Potassium is almost all picked up by the plant leaves from the water anyway. And, clay may already be in your "topsoil" in adequate amounts, but if not, there is clay almost everywhere in the world.
If you live near a river, look for deposits of river silt along that river, like at big curves in the river. Use that in place of the topsoil, and you have a very nutrient rich soil, which after being mineralized, is very good under pool filter sand.
The best substrate I have ever used, for good plant growth, was river silt topped by a layer of soilmaster, which is a fired clay product, but pool filter sand would have been almost as good.