Black Mountain Seiryu is the darker cousin of the well known Seiryu stone.  We personally like the darker grey, almost blueish tone that it has compared to regular light grey Seiryu.  The craggy texture and endless details in these stones allow you to easily create a natural looking aquascape.  
Seiryu may slightly raise pH and water hardness. Controsoil can help balance that out. 
Pieces from packages will range from 3-10 inches. If you have any special requests for sizes, please make a note when ordering and we will try to accommodate according to inventory.
If you are looking for larger stones, a minimum weight may be required. Larger stones = higher weight. Email our team if you need assistance!