10 to 15 pounds of stone will be sufficient for a ten gallon. Attached is a photo of 10lbs of Koke stone in front of a 10 gallon that I'm the process of setting up. Koke stone is more porous than Seiryu stone so you may wish to go with 15
+1 this is EXACTLY what I was going to say. Get more than you will need so you have some options. NEVER get rid of your hardscape. Trust me, you will need them eventually (try to convince my fiance though lol)Depends on your tank you should get more than enough so that you can be more flexible. Extra stone can be put aside, who knows when you are going to use it..
Rule number one, always keep your collection of hardscapes.
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