Agrocrete / man made LR

[Reefer Rob]

One of the mistakes I made was using the used sand from a previous tank in my rock mix. The sand was so loaded with PO4 it took a year to leach it out. It grew great algae for the first while.

I wouldn't use water off the roof to cure it, too many impurities will contaminate your rock. By the way it takes for ever to cure, allow 3 or 4 months at least.

Water softener salt mixed 50/50 with my cement/sand mix worked great for porosity.