Aquatic Nature Dekoline and Kh is the pH neutral and does not affect negatively the water. Grain size of between 1-3 mm gives good anchor for plant roots. Dekoline due. the grain shape provide good water circulation in the bottom layer. this gives the plants' roots O2, which in turn contributes to good uptake of plant nutrients. Dekoline has no sharp edges and is therefore not harmful to fish, for example. Corydoras. Using Aquatic Nature ABF bottom layer dekoline industry is very well suited to the top layer.