Here is a snippet from my build log RE: Hirocks.
I purchased 150lbs of the ââ"šÂ¬Ã…"œOur Bestââ"šÂ¬Ã‚ rock from these guys. These rocks are mined from a coral bed quarry in Hawaii, and the folks at HiRocks purchase them by the ton and have them shipped to CA.
When I received the shipment (about 6 business days after the purchase), I was a bit disappointed at first. The rock appeared very dense, plain and I thought that 150lbs would have gone a bit further volume wise. The fist picture is a picture of the rock as it arrived and after I moved it into a single large box.
The rock did appear very dusty, so my brother and I decided to give it a good rinse. When I dunked the first piece in, I was struck by how quickly the water got muddy. After agitating the rock for just a few seconds and pulling it out I was shocked. The rock was very porous, had tubes, coral skeletons, and even a clam fossil attached! The holes appear to have been plugged with sand and were further obscured by the dust created from mining/shipping. It took us about 30 minutes to rinse it all down good though several baths, we must have ended up with about an inch and a half of sand in the bottom of the first tub. Thatââ"šÂ¬Ã¢"žÂ¢s a few pounds of waste, but I hardly cared after being so pleasantly surprised with the quality of the rock.
The second picture is a picture of the rock rinsed off and stored in two 20 gallon Rubbermaid containers ready for placement in the tank. The last picture is a picture of a close up of some of the rock in my setup.