Do I Need Live Rock for a Successful Marine Aquarium?

Welcome to Simple Reefs. We have been talking about Live Rock as part of our series on staring a simple marine aquarium. If you have questions about what exactly Live Rock is, you should check out our article on Live Rock, Dry Rock, and Life Rock for a simple explanation. Today we are answering a very simple, yet very important, questions. Do I Need Live Rock?

Live Rock is Optional

Live rock is, strictly speaking, optional which is why we placed it in the Might Want to Buy section of our starting a Marine Aquarium guide. Now, I can already see marine aquarium vets turning their noses up and scoffing at that statement but it is true. It is completely optional and for a number of reasons.

Of course, we, obviously, have a whole bunch of marine fish keeping enthusiasts who simply don’t like the aesthetics of an aquarium filled with rock and choose to go for a more basic look. Other people simply don’t want the extra hassle of maintenance. Blowing off rocks, removing algae, etc etc. Whatever the reason, you can start a marine aquarium with no rock at all.

In fact, there are aquariums where live rock simply isn’t a recommend option. Keeping Seahorses, for example, where plants are far more appropriate. Other fish have been known to nibble at live rock creating a massive mess. Some people prefer to opt for macroalgae displays, as a whole, to differentiate their tanks from the crowd. Others just love having open space for their fish to swim around freely. Let’s take a look at a couple of scenarios where you can skip rock entirely.

I Only Want Fish

Great, you are on easy street as this is the most simple option you could possibly hope for. In fact, having a fish only marine aquarium takes the difficulty and expense down to around the level of a slightly more advanced fresh water tank.

You don’t need a sump, you don’t need live rock, you don’t need to dose, sand is completely optional, water changes will suffice for maintenance. You just need the basics. There are a few things to keep in mind since you won’t have rock to help with filtration and bacteria production.

You can’t start an aquarium as quickly as you can with rock as many people will add a piece of live rock to their aquarium to get the bacteria reproduction started, completing the all important “cycle” a lot quicker. You won’t have this option so you need bacteria to populate the surfaces of the aquarium, the substrate (if you have any), and whatever filter medium you have.

You are going to need to cycle your aquarium in the old fashioned way with a bottle of bacteria and a source of ammonia. We will go into this in a separate article but you need to be very sure that your cycle is complete before adding fish. This can take upwards of six weeks. It may even take longer due to less surface area for bacteria to populate. Supposed quick start, add a fish straight away, instant cycle, bottles of bacteria simply won’t work due to the reduced area to populate.

You will also need a more effective filtration system. One that can house a decent amount of space for filter medium to trap suspended waste particles and some bio media. Bio media is a type of filtration media that is very porous and has a ton of surface area for nitrifying bacteria to grow on. This will be very important in keeping your residents happy and healthy.

Fish poop a ton and that stuff needs to be removed. With larger fish, you will still benefit from additional filtration such as protein skimmers to help keep the water clean.

I Only Want Coral

Okay, this is doable too, and, in a lot of cases, is the preferable option. Afterall, how many coral tables do you see in fish shops that have live rock? If, for example, you are choosing to propagate coral, a shallow aquarium with no rock and lights suspended just above it may be the better option. Your coral won’t produce waste in the same way fish do. Your parameters can be kept stable with dosing. And water changes will keep everything fresh.

You can also take a deeper aquarium and use specific types of coral mounts to attach your coral to the glass. Bringing it closer to the light depending on need. It’s not as aesthetically pleasing as an aquarium filled with carefully placed coral taking up a large rock scape but it is easier to care for.

With no fish and only coral, your main concern is parameters such as calcium. Making sure there are enough of the elements in the water that your coral need becomes a priority. Though you will need to provide filtration, still, and water movement via wave makers etc. If manually feeding coral, you will benefit from better filtration and, perhaps, even a protein skimmer as many coral foods make the water very dirty.

I Want Fish and Coral

The problems come when you start adding fish to the equation. That lack of surface area for nitrifying bacteria to populate means there is less potential for processing waste. This can lead to higher levels of dirt in the water as a result of the waste.

One or two small fish shouldn’t be a problem. Lots of people keep a wrasse, or some other small pest eating fish, in with coral to keep things tidy. More than that, however, could be a disaster. With you frequently experiencing wild nutrient swings in the water that will make your coral very unhappy.

Situations like this will require much more careful planning and a much better filtration system. A sump can be used to mitigate a ton of these problems. You can fill your sump with a bunch of porous rocks or bio media blocks to increase bacteria reproduction. Keeping it out of sight but still reaping all the benefits of having live rock. You could also use canister filters in much the same way. Filling them with bio-media. Otherwise, you will likely encounter issues.

Do I Need Live Rock?

So, as you can see, live rock is completely optional. With that being said, in most cases, you are going to want to have a rock scape in your marine aquarium. The addition of live rock imparts a ton of benefits onto your aquarium and will make your life much easier in the long run. In most cases, it looks better, as well.

Over time, rocks in a marine aquarium will become populated by a range of beneficial bacteria and micro invertebrates. That’s what makes it Live Rock. It’s not actually live. It is just teaming with creatures that turn your aquarium from a barren wasteland into its very own micro-ecosystem. This ecosystem will help process waste in the water by turning it into much safer compounds that can then be removed with water changes.

If you are looking to add coral, you will benefit from having live rock. If you want fish, live rock will help keep them happy and healthy by increasing the amount of waste consuming bacteria to process leftover food and poop. If you want to house invertebrates, live rock will give many of them a place to hide and something to pick algae and food off of. Live rock has a whole ton of benefits.

But It Is Expensive

The problem with live rock, when on a budget, is the availability of it. It is very expensive, something we talk about in this article right here. You see, it’s not as easy to come by as it was years ago when fish shops would sell it for a few dollars per kilo. Thankfully, people aren’t allowed to simply chip away at live reefs, anymore, and eat the profit. Live Rock needs to be sustainable.

Nowadays, live rock has to be cultivated inside of an aquarium which can take many years. Even then, that live rock can be filled with parasites and nasties like Aiptasia. Hell, some live rock has been known to house predatory creatures like Mantis Shrimp that will grow in the rock, emerging at night to feast on your live stock.

This is a mine field and, most definitely, requires a series of articles to highlight some of the problems. We do have a simple solution, though, for budget aquariums. We start with something called Dry Rock; rock that has been dried out and contains no nasties or algae. And then we make it live ourselves by providing our own bacteria or by adding a cheap piece of live rock to the aquarium with it. You can read all about turning dry rock into live rock here and we also go over the pros and cons to this approach.

In Short

To make your decision on whether you need live rock, or not. Simply go back to what we said in our article on What Type of Marine Aquarium You Want? Picture your marine aquarium in five years time. Is it filled with fish and nothing else, do you just have coral, or do you have a bunch of fish, coral and invertebrates in there filling both the vertical and horizontal space in the tank?

If you only want fish, you don’t need live rock at all. Unless you enjoy the aesthetics of having a big rock scape and want extra waste processing capabilities. You can simply have a basic tank with nothing in it. If you are planning on owning seahorses or desire a plant based aquarium reminiscent of a freshwater tank, you can skip the rock altogether.

If, however, you do see yourself owning coral but also want a few fish. Essentially creating your very own slice of the reef. You may want to think about adding live rock from the very start. It can help you keep your water parameters stable. It will help process waste. You will have a more dynamic series of shelves to place your coral on, taking up the verticality in the tank. And you can use the rock scape to provide shading for less light intensive coral down on the surface.