I see recycled Reef rock for $5 / lbs, mainly Tonga and typically covered with coralline algae and micro and macro fauna. Typical rock is shown in the picture to the right.

I am on a constant search for a low cost, eco-friendly alternative to live rock and I feel I have a pretty good substitute now. I have made my own rock using oyster shells (whole shells), crushed shells and Portland cement (combined I call reefless Cement). What I have done is stacked large whole oyster shells in an nice looking pile and then cement them all together using my concrete with crushed shell aggregate. I then push crushed shell into the outside surface when wet. The end result is a nice looking rock that looks great in any reef tank and is great for base rock. I have some of these rocks in my tank, which turned them into live rock and encrusted them in coralline algae. The stacked whole oyster shells create many voids inside the rock which reduce weight and increase surface area for life. I am also using coarse salt in the mix, that dissolves when curing and creates further voids.

I have also made larger, platform rocks that are great as the main display rock.

I am selling this rock, fully cured, no aptasia, no nuisance algae, covered in bright purple coralline algae (which prevent the growth of other algae). Nice pieces, nice shapes for $3/pound. Much less than anywhere else in Bellingham, and MUCH nicer rock!

I also create live rock/shell rubble to cover the deep sand beds. This rubble of larger shell fragments, rocks, and pieces of my home made rock not only creates the living space for some of the macro life in your refugium, but also seeds various additional forms of algae, including the desirable purple coralline algae, and adds to your bio-filter.