Seiryu Stone varies in shades of grey with white veins running through the rock. Makes for interesting patterns in any Aquascape.
Will alter water parameters
Seiryu Stone Effects on Water Chemistry
When using rocks in aquascaping you need to be aware of the effects they can have on chemistry. Many stones contain carbonates, acids, and other elements that will cause minor to dramatic shifts in water chemistry.
Fish, plants, and invertebrates can be sickened or even killed with the wrong stone. As a very general rule of thumb, igneous rocks like granite tend to be inert while sedimentary and metamorphic rocks like limestone and marble tend to affect water chemistry somewhat.
Seiryu Stone, a metamorphic rock, is a bit troublesome because it has a strong effect on the pH of aquariums. To be precise, it contains calcium carbonate, both of which impact the GH (Calcium/Magnesium concentration) and KH (carbonate concentration) of an aquarium.
Taken together you’ll see an increase in pH and water hardness using this rock.
While neutral water in equilibrium with atmospheric CO2 (a weak acid) will show a slow increase in pH the various tannins and other molecules in most aquariums will accelerate leaching of calcium carbonate from Seiryu Stone.
Many fish, such as Livebearers and Rift Lake Cichlids, actually prefer hard water so the alkaline inducing effects of Seiryu Stone can be seen as a bonus. There are a couple of techniques you can use to mitigate this effect if you
Frequent Water Changes
Since calcium and carbonate levels will continue to rise regardless of what you do, water changes are the simplest solution. So long as there aren’t significant sources of acidity in your aquarium your pH won’t shift too dramatically.
Your usual small weekly water changes should be sufficient to mitigate the alkaline shift without impacting your fish and plants negatively. However if you tend to go longer between water changes the drastic shift in hardness can cause issues if you do massive water changes.
Another way to counteract the alkaline buffering capacity of Seiryu Stone is to include Driftwood, Indian Almond Leaves, Alder Cones, or better still, an acidic substrate like peat moss or ADA Aquasoil.
Aqua Design Amano (ADA) were the ones to popularize Seiryu Stone to begin with. This planting substrate helps maintain a pH more suitable for Cardinal Tetras, Cherry Shrimp, and the other inhabitants Amano often paired with Seiryu.