The materials
The materials used in the Back to Nature backgrounds include polyurethane, yet this does not say so much since there are many different kinds of polyurethane, some of which are not even suitable for aquariums. The mixture of polyurethane used in the Back to Nature backgrounds has been carefully tested for many years and does not release any chemical substances into the water which may be harmful to fish, plants and other living organisms in any way nor does it affect the chemical composition of the water. For this reason, Back to Nature backgrounds may be used in all kinds of aquariums, even marine aquariums.
Hard and durable surface
The special production process used in the manufacture of the Back to Nature backgrounds results in a surface which is extremely hard. This is why the backgrounds can withstand rather vigourous cleaning methods. The risk that the background will be destroyed by algae-eating catfish species with strong jaws is minimal (although some caution must be taken regarding some Panaque sorts which have been known to destroy "everything").
Underneath the hard surface, the material is more porous, making the background even stronger and more durable.