Has anyone used Hebel Masonry Block as tank rock-work material? This block is lightweight and easy to cut. It is manufactured from sand, cement, recycled material, lime, gypsum and an aerating agent, aluminium paste. It is moulded, cut and steam pressure cured in an autoclave.
As this building material is very easy to cut, you can easily make and carve "holey rocks". However, I found out that it actually floats and does not sink in water. Nevertheless, I have bleached it and have been washing it for 2 weeks now. I'm still thinking whether it will not be toxic to the fish (after bleaching and thorough washing) and how it will stay at the bottom of the tank. Any comments/suggestions?