Still relatively new and almost totally unknown over here: The substrates for planted tanks by Seachem. The Flourite substrates are highly popular in the US. These sands and gravels are very rich in nutrients, and they are an excellent choice for beautifully planted aquaria. We are proud to present these substrates here in a nutshell.
In our product range you can find the two Seachem substrates Flourite Black and Flourite Black Sand. As their names suggest, both substrates are black, and they only differ in grain size. (Flourite Black is a gravel with a grain of approx. 0.5 to 2 mm, Black Sand is a sand with a grain of under 1 mm). The nutrient composition of both substrates is identical. Please refer to the web pages of the manufacturer for an overview over which amounts of which nutrients these substrates exactly contain. We would like to mention, however, that they do not only contain important trace elements and iron that plants require but also macronutrients like potassium and magnesium.
Basically, Flourite substrates consist of special clay minerals from natural sources. For that reason, these substrate only contain natural nutrients and no artificial fertilisers. Just like standard sands and gravels, Flourite is a passive substrate that does not influence the water parameters. It is much more stable and heavier than any soil substrate and provides the plants with nutrients over an extremely long time (8 to 10 years). The plants actively take these nutrients up with their roots.
The substrates come pre-rinsed, however, please rinse them again thoroughly before using them in your aquarium. During transport, quite a bit of dust rubs off the grains, which may cloud the water if not rinsed off properly. Of course it also helps to fill the substrate into the aquarium carefully. If you plan on measuring your water parameters we also recommend pre-rinsing the substrate, as the smallest dust particles may falsify the results of some water tests. Apart from that, you can use the Flourite substrates just like any standard sands or gravels. Mixing them with other substrates like e.g. laterite is not necessary. Especially in the sand, planting is very easy. The gravel is ideal for realising substrate mounds in aquascaped layouts.
For planted tank keepers who have always used passive substrates, Flourite is a great alternative. The use of an optically pleasing substrate layer with underlying undergravel fertilizer is rendered unnecessary. Another upside of this substrate is the fact that nutrients remain available for an extremely long time, which puts the slightly higher price in proportion. Fluorite by Seachem is also an interesting choice for those aquascapers who have realised that active soils are of disadvantage for their purposes.
This substrate type is of course a great choice for tanks mainly planted with plants that use their roots to take up nutrients, like Echinodorus or Cryptocoryne and that are designed for a long life. In this type of tank, it is normally sufficient to almost exclusively fertilise via the substrate. In aquascapes or planted tanks with somewhat more demanding plant species that mainly take up their nutrients over the leaves we recommend adding liquid fertilizer in addition. Our range of Aqua Rebell fertilisers lends itself ideally to this purpose.