Curing Dry Rock for a Saltwater Aquarium

A Rocky Situation

This is the first segment in our series addressing our upcoming 12 gallon long saltwater tank build. Our hopes for this set-up is to over time cultivate it into a mixed reef tank. We will keep you updated every step of the way as we decide on our tech, layouts and livestock.

Our tank build actually began several weeks ago when we determined to go dry rock over live rock. Live rock is rock pulled from the ocean containing beneficial bacteria and other creatures, thus categorizing it as “live”. Dry rock on the other hand is typically rock pulled from the ocean and permitted to completely dry out. We have spent the last 6 weeks preparing our dry rock by leaching harmful elements and ultimately converting it into live rock minus all the unwanted hitchhikers. This article will be exploring the process we took to prepare our dry rock for introduction into our saltwater aquarium.  


Let’s tread water for a moment in our discussion to explore why we decided to forgo starting with live rock purchased at a lfs. Live rock is an extremely beneficial part of any saltwater aquarium as it helps to process waste such as nitrates. While you can choose to have a FO (fish only) set-up, many prefer to go with live rock due to the benefit of good bacteria and other helpful stowaways. However, live rock can also come with a host of harmful hitchhikers including: Flatworms such as acoel, segmented worms like bristle worms, bubble algae, and Aiptasia (pest anemones) to name a few. After a bad experience with bristle worms in my youth, I’m not eager to find these creatures in any of my future saltwater systems. In order to avoid introducing any headache inducing elements into our nano tank, we opted to start with dry rock.

Dry rock does not come with any damaging hitchhikers; however, you also lose any potentially helpful critters and beneficial bacteria. The good news is that over time you can cultivate dry rock into becoming live rock with any number of bottled “good bacteria” products. In order to propagate our beneficial bacteria levels, we utilized Seachem Stability and Instant Ocean BIO-Spira.

There is one drawback to selecting dry rock…………..time. Not only does it take time to increase the numbers of bacteria within your dry rock, but you will also need to cycle your dry rock. Since dry rock came from the sea, it contains once living organisms that have long since perished . When these deceased creatures on the rock are reintroduced to an aquatic environment, they will begin to decompose. Leaching ammonia into your system. Additionally, dry rock will seep phosphates into your tank (a main ingredient for algae outbreaks). The best way to remove these harmful elements is to conduct a curing process on your dry rock.  ​

Curing (sometimes referred to as cooking) is the process of cycling dry rock to remove phosphates and all dead particulate matter through the nitrifying cycle. During this process, good bacteria products like we discussed earlier can be added to encourage bacterial growth. To administer the bacteria, follow the recommendations written on the bottle. This beneficial bacteria will help to kick start the nitrogen cycle (converting ammonia to nitrite, then to nitrate and finally to nitrogen gas). Curing is accomplished by placing all dry rock into a container with saltwater which can be completely closed to prevent light from entering. This inhibits any type of algae growth during the process. A heater should be utilized maintain a temperature between 77 - 86 F to encourage nitrifying bacteria growth. During our curing process, we kept our curing rock at 81 F. A powerhead should also be used in order to have water movement throughout the container.

During the curing process, you will need to monitor ammonia, nitrite, nitrate and phosphate levels in hopes of eventually reaching a zero reading. Many testing kits are available on the market; however, for this initial process I relied on the API testing products. Once the initial nitrogen cycle has begun you should see ammonia level drop, followed soon after by nitrite. When we were conducting our cycling, the ammonia and nitrite levels dropped to zero within the first week. Nitrate and Phosphate levels, however took longer to drop. Nitrate levels took a spike at around week 3 and tapered off to zero at week 5. Phosphate levels continued to diminish to negligible levels at week 7. At this point we were ready to use our now live rock.

In total, it took us 7 weeks to successfully cure our dry rock. Length of time may vary depending on the amount of dead matter initially found on your rock. During this process we conducted full water changes several times. However, in the final two weeks of our curing we left the water unchanged to insure that all levels were remaining at zero.

Wow, I bet you never planned to focus this much of your time on rocks before. While you can get away without curing your dry rock if you plan to supplement with protein skimmers and reactors, it is always best to try limit the amount of these harmful elements from being introduced within your system. Remember that an ounce of prevention is worth a pound of cure. In upcoming installments, we will continue with our 12 Gallon Long Saltwater construction discussing aquascape and introducing our first aquarium inhabitant.

That’s all for this installment. Don’t forget to Keep Krill’in!