We are reader supported. When you purchase through links on our site, we may earn an affiliate commission. Also, as an Amazon affiliate, we earn from qualifying purchases.
There are a few things that most reef aquariums have in common. One of them is live rock used as part of the aquascape as a place to mount corals. Dry rock is popular for its affordability and the fact that it’s pest-free. It’s easy to use and easy to find. Dry rock and live rock are not the same things. If you’re new to reefing, the differentiation can be confusing.
Does dry rock become live rock? How long does it take for that to happen? The first thing to know is that rock is considered “live” according to its population of live bacteria. This bacteria filters your tank for you, populates by itself, and keeps your tank healthy. Like partially digested fish food, any food source will allow bacteria to begin inhabiting your rock. This process doesn’t have a set time frame for occurring, but you can use booster products to speed it up. Live sand also helps shorten the time frame for creating live rock, as it already contains proliferating bacteria. Regardless of what you choose, anything you place into your aquarium will become live in a matter of weeks, and there’s nothing you can do to stop it.
Dry rock (or anything else in your tank) will become live in a matter of weeks no matter what you do. There are a few reasons for using the dry rock to improve your aquarium environment.
Does dry rock ensure a clean aquarium?
No, but it limits the opportunity for pests to invade. Live rock is the biggest source of unwanted pests in a reef aquarium. Instead, buying dry rock seriously limits the chances of unwanted pests being introduced to your tank. Before adding them to your aquarium, it’s also recommended to carefully inspect and quarantine corals, snails, fish, crabs, and any other living creatures.
Does dry rock take longer to cycle your tank?
Cycling live rock takes about two weeks longer than cycling dry rock. Using live sand or other bacterial boosting products can help compensate for this. Bacteria proliferate quickly on their own. Within a few weeks, you will have billions of microscopic bacteria in your tank to break down nitrates and ammonia. Snail shells or patches of coralline algae from an established reef aquarium can add good bacteria strains and other creatures to help speed up the cycling process.
Will algae grow on the dry rock?
As long as you add an initial source, algae will grow on dry rock. You don’t need much; a small bit on the bottom of a coral or a live rock from a trusted, established tank will do just fine. Scraping it off and dropping it into your tank will help it to spread quicker.
Some aquarium owners report seeing coralline algae growth within two weeks, while others find it takes a year or more to get significant growth. The best way to promote growth is to maintain calcium and alkalinity levels in your tank and always keep algae fully submerged—large water changes or exposing algae to air significantly stunt its growth.
How do you care for dry rock?
Dried versions of Fiji and Pukani rock come from the same place as the live versions. Both have organic material that should be broken down before placing the rocks in your tank. These will break down further into nutrients like phosphate and nitrate.
Since no one wants to start a new tank with these excess nutrients floating around, all rock should be cured, whether wet or dry. This is simply the process of removing as much organic material as you can by hand, by hose, or by soaking the rock in heated saltwater for a month or two before adding it to the aquarium. While you can use bacterial boosters to speed up the process, it’s usually best to let nature take its course and wait a few short weeks for the process to complete itself.
Benefits of using dry rock
The dry base rock provides you with more control over the ecological development of your reef. It is free of organisms that will die and cloud up your water, and base rock doesn’t require the curing period that is normally required. Over time it will change into live rock full of anaerobic bacteria.
Dry rock is sourced and extracted in an environmentally responsible manner. It comes from ancient, dried-up coral reefs rather than being harvested from a living reef. It is porous and lightweight, making it cost-effective, and for purists who want authenticity in their reef aquariums, nothing could look more natural.
Downsides of using dry rock
The biggest downside to using dry rock and waiting for it to become life is the amount of time it takes to cycle. Most aquarium reef owners report that it’s well worth it when starting a new tank as you won’t have issues with pests and invasive bacteria long-term. This pest avoidance is the most important reason to use dry rock at the start of a tank.
Dry rock is an easy, cost-effective way to gain live rock in your reef aquarium. Dry rock does take a few weeks to cycle into live rock but avoids the introduction of unwanted pests into your tank. The cycling process can be sped up using bacterial boosting products and maintaining your water conditions.