01-11-2012, 02:02 PM
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I do not recommend soil. I'll explain why; but first, let me say that soil can work and work well. But it does carry issues, and I do not consider that the minimal benefit of soil is sufficient to off-set what can often occur. It is possible to have a lush "forest" planted tank without soil. The attached photo of one of my tanks, the 70g flooded Amazon forest setup, illustrates this.
Soil is the most involved method of setting up a planted tank, and if done properly it can take months to become "established." During this period, most sources do not recommend adding fish to the tank. And from all my research to date, the only benefit to soil that I have been able to discern is additional CO2 from the outset. There is no nutrient benefit. All aquatic plants obtain their nutrients from the water column. Nutrients contained in the "soil" have to enter the water column before the plant roots can assimilate them, same as terrestrial plants. This is why you can use plain sand or fine gravel and add nutrients into that substrate and the plants will benefit just as much. The CO2 initially is greater because there will be more bacteria in the soil to break down organics; but organics and nutrients in the soil get used up and have to be added from then on. And this also occurs with sand or fine gravel, it just takes a bit longer initially to establish the biological system.
Your two inches of sand will be a very suitable substrate. As someone mentioned, the only plants benefiting from nutrients in the substrate are substrate-rooted plants. Nutrients can be added via tablets for heavy feeding plants like swords, but liquid nutrient fertilizing via the water column will suffice all aquarium plants.
The most important equipment in a planted tank is the light. Without good light plants will not thrive, and might die off. Good light means sufficient intensity for the type of plants you want--and there are differences--and a good spectrum. We can go into this more later, but you might find useful information in the 4-part series "A Basic Approach to the Natural Planted Aquarium" stickied at the head of this section of the forum.