I read an article years ago about a guy that uses Supersoil and silica grit. It seemed a cheap way to go and I tried it for several years. You get really good plant growth, till the plants become rootbound. This takes several years. You place a 2 1/2" layer of damp SuperSoil in the tank and cover with a 1-2 " layer of Silica sandblasting grit. Pour your water into the tank with a plate on the grit. Once the tank is about half full, plant the plants into the grit. Finish by adding just enough grit to cover any soil you may have exposed and finish filling the tank. The water will be tinted pale brown for a while, but will clear. You will get some bubbling as the lower soil layer decays and the soil will become more compacted. I used this system with diy co2 and home made hood. This approach does have drawbacks such as pulling up soil when removing plants and root compaction, but does offer a low cost way of enjoying a planted tank. This also might be a really good way to grow plants to sell. Of course I do not know how well this would work in locations where you have soft tap water. I live in the desert of Ca and my water is liquid minerals.