The Real Reef rock is a man made rock that is then tanked in a greenhouse for 3-4 months in a large established system to start populating it with bacteria. It is a bit dense, but the structure is really good, and if you're going for that "green aspect" of reefkeeping then this is a no-brainer. You will not get the same phosphate leaching, and unwanted nuisance algae growth that is common with dry rock when using this product. If you're going for the most amount of biodiversity and life then the Fiji and Manado would still be the way to go for you.