Another new member

[new but handy]

Morning.
Use portland cement mixed with reef sand also if you mix in rock salt (driveway salt), after you cure the rock it all dissolves and leaves very porous rock. The rock has to be cured for along time(I left mine for 4 months)
I cured mine in a rubbermade bin full of fresh water, I also did a water change every week or so.
If you use rock salt, you have to be carefull how much, or the rock just falls apart