It's not too bad in this tank due to the high barriers but there has been quite a lot spilling through the gaps in the cobbles in my Rio tank. However every water change I just syphon them up with all the muck in the water change, rinse them off and put them back at the back of the tank. As it's so light and larger particles than the sand they sit on top rather than getting mixed in.Papillo said:I think I still want the sand - I like to see the full range of behavior in my fish. So how are you finding your split substrate? Are you getting much mixing of the AS and sand?