Some preparations include the construction of considerable differences in level on the back of a tank, say more than 20 cm.
Usually are made ​​using the background material and are also useful because some plants with large root system receiving a considerable thickness of the substrate ... but in some cases it is clear that the purchase of bags and sacks of lands "special" of various types can be VERY expensive.
Take, for example, who prepares large aquariums using the excellent and precious and expensive materials of the ADA, known Japanese company.
Alternatively it is also widely used Flourite, but she does not joke with her ​​about 30 € for 7 kg bag ...
I can suggest 2 options that I think good, but personally I have not got to try in my aquarium

  1. mixed with the substrate of the GRAVELIT PetCompany (or find it on sale), however with a very porous loam.
    I did not exactly provide a link because I'm still looking for this product for sale online ... I've read of many who have bought in hypermarkets, I still have not crossed ... but I will try again. :-)
  2. insert underneath it all a nice piece of spugnona compact, that can withstand the weight, but perhaps not yielding deforming in full.
    As in this aquarium Massimo Faberi
    I like this solution because, although I'm not convinced it's cheapest Gravelit, is aesthetically less impact, because the Gravelit however, you should mix the rest of the soil, putting it back in sooner or later ... unless "bridle" in some so this substrate. Some use a plastic or aluminum mesh ... but we must also find links to the right because the roots can get in, as well as water ents, but the gravel can not get out.

Both of these solutions can become a substrate for the settlement bacterial, even if in the case of the sponge, however, would hardly be a reservoir of nutrients, in contrast to the Gravelit ... The advantage instead of the sponge is that the water would flow in its interior more easily, and then would reach even more oxygen and would avoid potential anoxic areas (without oxygen) in the case of funds particolamente high (say above 20 cm).

For my next layout will try first of all Gravelit to create differences of up to 20 cm, if I see that coming at a greater height then I also doterò sponge or sponges to support the fund.

Update: I finally used different pieces blue sponge, and I found myself well.