Live Rocks and Dry Rocks: Pros and Cons

Live Rocks and Dry Rocks Pros and Cons

Rocks go a long way in decorating marine aquariums hence making the tanks aesthetically pleasing and giving off a long-lasting impression.

Now, the topic of discussion is the choice of aquarium rocks, there seems to be an overbearing discrepancy when it comes to this— with many opting for natural or live rocks to add to their reef tanks while others have a fondness for dry rocks due to a number of justifiable reasons.

In this article, I will be exploring the features of live rocks and dry rocks, in addition to their pros and cons to allow aquarists to choose which is best for them without contemplation. Let’s get right to it!

Live Rocks and Dry Rocks in Reef Tanks: A Brief Definition

Live Rocks:

Well, of course, do not take it literally! These rocks are deemed “live” only because of the presence of microorganisms (such as bacteria, algae, etc.) and small invertebrates  (worms, snails, crabs, mantis shrimp, etc.), residing on and within their porous structures.

Since live rocks are harvested from marine environments, they play a crucial role in establishing and maintaining biological filtration in a reef aquarium, aiding in the cycling process and contributing to the overall health and stability of the marine ecosystem.

Dry Rocks:

On the other hand, dry rocks are inert, non-living rock formations that lack the live biological components found in live rocks.

Although dry rocks do not introduce living organisms or microorganisms into the aquarium immediately, they offer aquarists the opportunity to cultivate and shape the tank’s biological balance over time.

Important:

Semi-dry/live or Wet Rocks

These rocks are also sourced from the ocean. The main difference with live rocks is that they generally undergo a very long transportation and subsequently dry out during (or even before) shipment.

It is crucial to understand that these rocks only look dry but in reality, they still harbor a substantial number of different organisms in a dormant state.

Thus, if used without proper treatment (cure), there is still a significant risk of introducing unwanted guests into your reef tank.

Live Rocks: Pros and Cons for Reef Tanks

Pros:

  1. Instant Cycling: Live rocks provide a faster start for the aquarium. They allow almost immediate establishment of the nitrogen cycle.
  2. Natural Aesthetics: They often exhibit unique textures, and colors, enhancing the visual appeal of the reef tank.
  3. Biological Diversity: These rocks come with a rich array of beneficial microorganisms, contributing to a diverse and self-sustaining ecosystem.
  4. Habitat Enhancement: Live rocks offer natural hiding spots and breeding grounds for marine life, fostering a more dynamic and natural environment.

Cons:

  1. Cost: Live rocks are very expensive, making this hobby, which is already quite costly, even more expensive.
  2. Weight and Density: Live rocks are generally denser and heavier (because they also contain some water) than their dry counterparts. It makes them more difficult to work with and potentially impacting tank placement and stability.
  3. Potential Pests: Unfortunately, besides beneficial microorganisms, these rocks may also introduce undesirable organisms or unwanted parasites that could harm corals or fish.
  1. Water Contamination: Ideally, live rock should carry the invigorating scent of the sea, not a foul odor. If live rock is mishandled or is subjected to overheating (in summer) or excessive cooling (in winter), during transportation, there is a risk that a portion of its microorganisms may die off.
    This will trigger a process of decay and decomposition when introduced into your aquarium. As a result, it may lead to ammonia spikes and phosphorus release, potentially compromising the water quality in your tank.
    Note: Ideally, the transportation of live rock from supplier to buyer should be within 36 hours.
  1. Ecological impact. Live rocks are taken from the ocean. The destructive nature of this practice is already illegal in some states.

Dry Rocks: Pros and Cons for Reef Tanks

Pros:

  1. Low Risk of Pests: Dry rocks have a very low risk of introducing pests to the aquarium. You should not worry about introducing Firewormsmantis shrimpAiptasiaBubble algaeVermetid snails, Gorilla crabs, Montipora-eating nudibranchs, Dinoflagellates, etc. Yep, this list is actually huge!
  2. Cost: The cost of such rocks is significantly lower. Their price won’t break the bank and is budget-friendly.
  3. Easier Handling: Dry rocks are lighter and easier to handle. They are free of water. It also simplifies the aquascaping process.
  4. Customization: Dry rocks offer more options for aquascapers to design their ideal underwater landscape. They have lots of different types and shapes. Some of them may even look like live rocks.
  5. Sustainability: Sourcing these rocks from non-marine environments can contribute to more sustainable practices in reef tank setups.

Cons:

  1. Slow Cycling: Dry rocks cannot cycle the tank on their own. These rocks do not introduce living organisms or microorganisms into the aquarium immediately.
  2. Initial Sterility: The lack of live organisms means the tank starts with minimal biodiversity, requiring time to develop a thriving ecosystem.
  3. Artificial Appearance: Some aquarists may complain that dry rocks lack the natural aesthetics of live rocks.

How Live Rocks Work in Reef Tanks

Thanks to the porous structure and composition, live rocks form a unique community of micro-, meio-, and macro-benthos, constituting a complex ecosystem within the marine aquarium.

The pores of live rocks become habitats for a variety of marine life, serving as feeding grounds, respiratory sites, and waste elimination areas. This creates a continuous water circulation through the rock, essentially forming a distinctive yet highly effective biological and chemical reactor.

As micro and macroorganisms introduced with the live rocks populate decorations, substrates, and biofilter media, they contribute to an increase in biological diversity. This, in turn, enhances the overall resilience and stability of the aquarium system.

Can Dry Rocks Become Live Rocks?

Absolutely! As I mentioned before, what really brings a rock to “life” is the population of live bacteria that acts as your tank’s natural filter.

Over time, these bacteria will colonize your dry rocks as well. This is an inevitable and normal process. Therefore, your rock will gradually become home to a lively mix of microorganisms and coralline algae turning it into a living part of your aquarium.

Anticipating the next question, I will say it right away that there are no specific timelines for when dry stones will transform into live stones because it largely depends on your aquarium. Typically, this process takes a minimum of 3-4 months, but in some cases, it can extend up to a year.

Factors Influencing Duration:

  • Type of dry rock. Rocks with high density and small pores will take a longer time to undergo such transformation.
  • Water parameters and temperature. If your water parameters are not optimal, the process will take longer.
  • Whether beneficial bacteria is used. The addition of nitrifying bacteria (such as BIOSpira) can shorten the overall duration. This is because it kickstarts the development of the nitrogen cycle, leading to the establishment of a more mature and stable ecosystem.

How Many Rocks Do I Need?

As a general guideline, a common recommendation is to have about 1 to 1.5 pounds of rock per gallon (or 2 – 3 kg per 4 liters) of aquarium water.

The optimal quantity of rocks in a marine aquarium depends on several factors, including the tank size, the specific needs of the inhabitants, and the desired aesthetic. For example:

  • For fish-only tanks, it should be roughly around 10-20% of the aquarium’s volume since fish require more space.
  • For reef tanks, it is advised to have anywhere from 20 to 50% of the aquarium’s volume as rocks.

As we can see, this is a flexible suggestion, and the ideal amount may also vary based on individual preferences.

Most Popular Options of Dry Rocks

Here’s a list of some commonly used dry rocks in the hobby:

Live Rocks and Dry Rocks Pros and Cons - Reef Saver Rock1. Marco Rock/Reef Saver Rock: It’s often made from fossilized coral skeletons or limestone, providing a calcium carbonate-rich structure (just like live rocks). These rocks are appreciated for being environmentally friendly, as they are harvested from dry land and do not involve the direct removal of living coral from the ocean.

It is known for its porous nature, which allows for beneficial bacteria to colonize and contribute to biological filtration in the aquarium. Additionally, its shape allows the edges to fit together really well it is nearly perfect for aquascaping.

Live Rocks and Dry Rocks Pros and Cons - Pukani Rock2. Pukani Rock: Known for its interesting shapes, high porosity, and weight. This is one of the lightest rocks in the hobby, meaning you get more rock for your money.

At the same time, because of such a structure, its pores can trap more dried-up stuff than others. So, it is good to soak the rock in water for a few weeks.

Live Rocks and Dry Rocks Pros and Cons - Fiji Rock3. Fiji Rock: These dry rocks are often chosen for their density and diverse formations. These rocks also have a nice smooth surface, so they’re easy to clean before putting them in the tank and keep clean in the long run.

Live Rocks and Dry Rocks Pros and Cons - Tonga Rock4. Tonga Rock: Recognized for its unique shapes and texture. Aquarists appreciate Tonga Rock for its potential in crafting visually appealing and unique underwater landscapes. However, it can be difficult to work with them for beginners.

Types:

  • Base Rock: Generally serves as a foundational element for aquascaping.
  • Branching Dry Rock: These dry rocks offer a distinctive branch-like structure for unique aquascaping. Aquarists often choose these rocks to provide elevated surfaces for the placement of branching corals, enhancing the overall aesthetic of a reef tank.
Important: I would not recommend experimenting with other types of rocks, especially if you have no experience.  They may be not effective as a biofilter (for example, because their structure can lack sufficient porosity) or simply be dangerous (because of their weigh).

Curing the Dry Rocks

To be safe, it is generally recommended to cure dry rocks before adding them to your reef tank. This process helps prevent potential issues, such as spikes in ammonia and phosphates, which could negatively impact water quality.

How to cure dry rocks:

  1. Rinse: Rinse the dry rocks under running water to remove loose debris, dust, and any surface impurities.
  2. Clen: Use a small brush or, if the rock structure allows, tweezers to clean it.
  3. Soak: Submerge the rocks in a clean container filled with saltwater.
  4. Observe and Test: During the curing process, monitor the water for any discoloration or foul odors. Test for ammonia, nitrite, and nitrate levels to ensure they stabilize over time. Change the water every few days to help leach out any remaining impurities.
  5. Optional Bleaching: If you encounter persistent issues or want to be thorough, you can consider a diluted bleach solution (1 part bleach to 10 parts water) for a short soak.

Depending on the level of impurities and the specific rocks, the curing process may take several weeks. Be patient, and continue monitoring water parameters until they remain stable.

In Conclusion

Almost all hobbyists want a bit of the real sea in their tanks, and I get that. Live rocks are beautiful and let you set up your reef tank almost right away. Nonetheless, there are a lot of issues that come with using them.

So, in my opinion, going for dry rocks makes more sense. Plus, the cool part is that your dry rocks will turn into live ones eventually, and that’s interesting to watch too!

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