For my new tank, I'm going to be doubling up the amount of liverock, as the new tank is double the side of the current tank... (3x2x2 -> 6x2x2).
To save on money, and for fun, I'm going to try and make some "aragocrete".
It's essentially cement mixed with some sort of fish safe substrate, like aragonite, crushed coral or crushed oyster shells, then shaping it to looks like liverock, and curing it for 2 days in air, and 6-8 weeks in fresh water.
I've read quite a lot about it, and the big issue with it appears to be making sure the cement is properly cured. This can be checked by testing the PH of the water before the rock goes in and a few days after, while stopping any airation of the water to see if the PH has risen. If the PH stays stable then it should be cured, if not, replace the water and check again in a few days..
I'm going to try my own recipe for my "aragocrete" / "livecrock":
cement
crushed coral gravel
perlite
The perlite should be fish safe (not 100% sure though), and it will decrease teh weight of the rocks, as it is essentially volcanic glass with tiny airbubbles trapped inside.
For further reading:
http://www.geocities.com/CapeCanaver...ementRock.html
http://www.athiel.com/lib10/rockmaking.htm
http://www.athiel.com/lib11/garfcont1.htm
If anyone has any experience with making their own liverock, please share with us!