DIY lava rock caves and rock formation.
So im thinking in going to go to my local hardware store (lowes or menards) and pick up some lava rock (prolly dark red and black) and try and make a decent size rock structure for my upcoming 55g. I want it to pretty much take up the left side of my tank. im talkin big structure. so i was lookin for some tips about how to make it structurally sound, also what to use to bond the rocks together so they look good and dont hurt the tank. im probably going to make some caves in the rocks too.