OUCH! I kept thinking about how I had seen reefs being rebuilt in the Gulf of Mexico with everything under the sun, but especially these huge concrete wheels that were chained together. So why not concrete in a reef tank?

I researched this site which had a ton of useful information, GARF.org. Great site with a lot of insight into coral keeping. I read about the successes (and failures) of people who were attempting to utilize concrete reef rock, and I became convinced that it was a viable alternative to traditional "live rock".

I made 3 separate batches in the initial casting phase, producing the rocks you see here. The outline is for a 48" by 18" tank, my first choice of a 90 gallon tank. I setup the rocks and cast pieces allowing them to interlock on the reef. I wanted a stable base, but yet plenty of flowthrough. The "sand" was CaribSea sugar sized aragonite, and the "gravel" was Caribsea coarse aragonite. The plastic shavings came from under the saw of a local plastics fabricator.

The large cave rock above on the bottom of the picture was cast with a large Rubbermaid dishwashing glove inflated with air and tied. The fingers produced holes out the back for water flow.

The casts were done in both aragonite gravel and in beds of Aruba crushed coral. The aragonite sea gravel produces a very white rock as you can partially see above. There are 2 other distinct surface types, the browner is the crushed coral, and the dark grey was mix that was exposed above the cast. It will be interesting watching the three surface types mature in the tank.

The most important thing is to cure the rock of the lime which is released by the cement. If this is not done correctly, you'll toast the ph in your tank and you become a mark in the "tried it and failed" column.For my curing phase I purchased these plastic red bins (with lids) for $8 each at Target. They will be handy in the future for other things as well. And I had an old trash can that wasn't being used.

The first soaking I mixed 2 gallons of vinegar into the 3 containers in equal proportions. I closed the bins up and let them sit in the hot Arizona sun for 10 days. This was pulled out, containers and rocks rinsed, and then followed by fresh water on a 10 day change cycle for the next 60 days. Then a subsequent change and now they have been soaking for 30 days. This is a much longer period than what is suggested, but I had the time and it only helps stabilize the rock more. It was not until about the 50 day mark that I no longer had a "white scum" floating in the bins.