Using the proper substrate set up in the planted aquarium can really make a significant difference in the overall success of the plants. This is one of those cases where a little bit of preparation can give really good returns. When planning your planted aquarium, you have a couple of options to consider. Do you want to use only a true plant substrate or mix it in with a standard gravel based product? Will you add one of the nutrient supplements with the substrate or provide these later?
While success is possible with standard gravel based set ups, the use of a true plant substrate provides many advantages. Most of these substrates are a clay-based material, generally with a 2 to 3 mm size. This size prevents the substrate from packing down and creating dead spots. Finer material would pack preventing proper nutrient flow through the substrate. Larger pebbles can lead to the development of detritus traps in the void spaces. The recommended clay-based substrates additionally have a very porous structure. This allows a better rooting structure to develop and anchor your rooted plants within the substrate. The clay substrate will also leach small amounts of the important nutrient iron (Fe) into the water over a very long period of time. This porous material will absorb nutrients and trace elements that you are adding to the aquarium, helping to concentrate them near the root structure. The internal pore structure also allows development of anoxic microenvironments as found in natural habitats. This aids in the uptake of many trace elements by the roots.
As good as these substrates are, it can be a real boost to mix in a separate nutrient/trace element supplement when first setting up the planted aquarium. Available products include laterite based material, timed released granules or granules designed to be extracted by the root structure. Generally you mix these supplements in a 50:50 ratio with the plant substrate and place the mixture into the aquarium first, providing 1 to 2 inches of material. Then you layer another 2 to 3 inches of the clay substrate over top of the mix. For best results, remember to rinse all substrates before adding to the aquarium to remove excessive loose material that will cloud the aquarium. Once all of the substrate is in place, it is best to fill the aquarium with a hose or pour the water into a bowl to prevent upsetting the substrate. Later, when it is time for routine maintenance and gravel vacuum the substrate, be sure to only vacuum the top two inches to avoid removing the nutrients from the lower layer.
If your planted aquarium is already set up and you wish to add some rooted plants with a good substrate, you can place the substrate and plants in a small ceramic pot and bury this pot in your standard gravel. You can even mix some of the supplements or laterite into the pot. You can also use tablet/cone style supplements near the roots of your plants in the gravel. Tablets provide necessary trace elements to a six-inch diameter area for up to three months.
When planning your landscaping, gently slope the substrate for best results, with higher levels at the back of the aquarium. If you wish, you can use small pieces of shale or rocks to make a terrace wall to develop a deeper area. This can provide a dramatic focal point in your planted aquarium. The use of natural stones and driftwood can help finish out the general design. As the plants thrive in your aquarium, they will fill in the rest!