Sand bed

[Mrsadat]

Hell fellow reefers, I set up my reefer 250 in April, two months after I noticed in a few spots in the sand bed the sand somehow suddenly became hard like rock, didn’t think much of it at the time I just took it out the tank and threw it away. Today while inspecting the tank I noticed it again in a different spot any idea on what would cause this?

 

[P-Dub]

High CaCo3 is usually the root cause. What are your Ca & Alk levels? High levels can cause precipitation and solidification of the substrate. This is a general but not always situation.