Explaining The Difference Between Live Rock, Dry Rock & Life Rock - What Are The Differences?

Welcome to Simple Reefs. Today we are continuing our series on starting a simple and affordable marine aquarium. This article expands on our look into the things we Might Want to Buy for our new Marine Aquarium. Today we are looking at the role Live Rock plays in our marine aquarium and whether or not we need it. We are also taking a look at the differences between Live Rock, Dry Rock, and Life Rock.

The Marine Aquarium Difference

There are a few major differences between Freshwater aquariums and Marine. The most obvious of which is the aesthetics. Your average freshwater aquarium will, likely, feature a bunch of fish and a substrate consisting of some type of gravel or sand. Some may include a few pieces of driftwood or slate for hiding places and decoration. Some may even add a few plants and, perhaps, some rather out of place ornaments painted in a suspicious shade of toxic green.

Your typical marine aquarium, however, will look a lot different. It’s rare to see aquatic plants in a marine aquarium and plastic or resin decorations are extremely passe. Any type of wood centre piece is unlikely and the, general, aesthetic is far more geared towards replicating the undersea environment of the aquarium’s residents.

The Foundation of a Reef

One thing you will see, in the vast majority of marine aquariums, however, is an elaborate rock structure taking up a large proportion of the real estate in the tank. This structure may consist of archways and bridges, multiple island rock formations, a combination of both, or one large connected rock-scape with varying height levels and integrated caves. These structures are made from, what is known as, Live Rock.

When we talk about Live Rock, we are referring to the large rock based structures that you see forming the basis of reefs, both natural and synthetic. When you see photos of people’s glorious marine aquariums, full of coral. They all started with little more than rock. The rock forms the structural backbone of a reef aquarium and plays a hugely important role in making your tank function like a real mini ecosystem.

Why Do We Call it Live Rock?

The reason we refer to it as “Live Rock” rather than just “rock” is not because it is actually alive. In fact, Live Rock is very much dead. To a point where it is, typically, made from the skeletons of coral that have been gone for a very long time. Or from other calcareous organisms that expired in the past. That’s where the aragonite that makes up the rocks comes from.

We, actually, call it Live Rock because of the various different organisms that exist on its surface and inside of its cracks and crevices. If you were to take an up close look at a piece of live rock. You would see hundreds of small invertebrates, molluscs, algae, and other such things. On a microlevel, you would see millions of bacteria. It is these things that make the rock Live. A more sensible name would be “rock with lots of living organisms inhabiting it” but it just doesn’t have the same ring.

These are the things that, as marine aquarium owners, we desperately want in our tanks. We want biodiversity so we can develop our own mini-ecosystems full of bacteria that will serve a number of different, massively important, purposes. I should clarify that when we say bacteria, we don’t mean the bad kind that can make you very ill. We mean the very important kinds of bacteria that are imperative to the success of our aquarium.

A Bacterial Wonderland

The rock, not only, provides nooks and crannies for the numerous wee-beasties that make up our miniature ecosystems. It also provides extensive surface area for billions of bacteria to populate and reproduce. This bacteria plays an important role in our aquariums. When you throw food into your tank and your fish eat it. Some will be left, the rest will be turned into waste. This waste and rotting food results in a dissolved toxin known as ammonia accumulating in the water.

Luckily, the bacteria in our fish tanks consumes the ammonia produced by fish waste, and food, and processes it into a less harmful (to marine fish, anyway) compound called “Nitrite”. This Nitrite is then, in turn, processed, by a different type of bacteria, into the far less harmful compound “nitrate” in a process called Nitrification. Without the bacteria in our aquariums, Ammonia would quickly accumulate. Ammonia will harm fish in the short term, eventually killing them very quickly when it reaches certain levels.

We absolutely need this bacteria. When people talk about “Cycling” your new aquarium, that is what they are referring to. The process of building up a bacterial profile so that the ammonia in your water can be dealt with by the nitrification cycle. Live Rock helps with this, tremendously. In fact, a decent sized chunk of Live Rock can rapidly speed up the Cycling process. Providing a bacterial profile that will then reproduce at a rapid rate. This is something we will go into in a future article.

Most reef aquariums will house a substantial amount of live rock. Meaning the nitrification process happens much more quickly and much more effectively. In fact, the bigger our aquarium and the more inhabitants we have in it. The more rock we want to have to help process all of that extra waste.

It’s pretty simple, really. The more live rock you have, the more surface area you are afforded for bacteria growth, the more ammonia you can process, the more tank residents you can accommodate. On top of that, the more hiding places you have for your fish and other critters, and the more places you have to mount coral based on their need, or lack thereof, for light.

So What is Dry Rock?

Dry Rock is exactly what it sounds like. It is rock that has been removed from the water and is completely dry. Everything that may have, once, lived on the surface of the rock is dead, much like the rock itself. There is no bacteria on the dry rock. There are no organisms hanging out in there waiting to be plopped back into the water. There is no algae, no parasites, and no beneficial creatures.

Dry Rock comes in many forms. You can buy perfectly white aragonite dry rock that looks like it has been soaked in bleach. Absolutely pristine and completely clean. At least on the surface. You can buy dry rock that doesn’t look like it came from a reef at all due to it’s much less porous nature.

You can buy dry rock that still looks live in as much as it has residual coralline algae or the remnants of the organisms that once called it home. Or you can buy dry rock that was only recently removed from an aquarium but was stored incorrectly.

Either way, they are all classed as dry rock and all should be considered to be dead. Many marine aquarium hobbyists start their rock scapes with dry rock. After all, it is parasite free so, in many ways, seems like the safest option. It is, almost always, the cheapest option, as well. But there are things to consider when starting with dry rock which is something we will get into in a future article.

How About Life Rock?

So we have talked about Live Rock and we have discussed Dry Rock but what is this Life Rock stuff you see on Amazon and online aquarists? Well, Life Rock is something of a middle ground between Live Rock and Dry Rock. It is made by Carib Sea, though other companies offer similar alternatives, and it is, basically, dry rock which has been painted shades of pink and red to look as though it is heavily encrusted with the very desirable algae known as Coralline algae. Giving the impression that it is live. It is then infused with some beneficial bacteria that will stay dormant until you add it to your aquarium.

Crabisea claims that Life Rock will speed up your cycling process when you have a new tank. Preventing what is known as “New Tanks Syndrome”. It does this by the bacteria added to the rock quickly coming back to life and getting to work on processing the ammonia in your water.

Life Rock is, in my opinion, potentially a better option to start with than Dry Rock. I have, in all honesty, only ever added it to an existing display so it is hard to comment. I never noticed any big problems with algae on the surface of the rocks and they look much better when added to an existing display thanks to how weathered they appear to be. Still, they are an incredibly expensive option and come at a high premium for questionable benefits. We will talk about it more in a future article.

So What Should I Do?

This is the big question, right? Well, after you have answered the question of whether, or not, you actually need Live Rock in the first place. What should you do if you want a tank filled with Live Rock? Particularly if you are trying to set a marine aquarium up on a budget. I mean, you could just head out to your local fish shop and purchase a whole bunch of live rock to fill your aquarium with. That would have you off and running in a jiffy with a tank that is fully cycled and filled with plenty of bacteria, invertebrates, and algae. But have you seen the prices?

Live Rock is extremely expensive. Ranging anywhere from £12 per kilo to over £25 per kilo. In fact, it is so expensive that I just put together this article on Why Is Live Rock So Expensive that you should really check out.

When it comes to the best thing that we can do, on a budget, we have a couple of options that can save us a ton of money. All of which revolve around purchasing Dry Rock and transforming it into Live Rock, ourselves. We can do this a couple of different ways. Each of which has a few pros and cons.

We can start with Dry Rock and utilise a single piece of Live Rock to help transform our Dry Rock into Live Rock. Or we can, simply, use a bottle of starter bacteria that we add to the tank with our Dry Rock to make it live. Let’s save you some serious money by moving on to our article on Live Rock On A Budget – How to Build an Affordable Rock Scape.