Live Rock & Dead Rock – Aquascaping, Coralline Algae, & How Much

You may have a lot of questions about live rock. What about dead rock? What’s coralline algae? How much do I need? What are some aquascaping best practices? The most important thing to know about live rock is that it is the backbone of your filtration system. It is essentially dead coral that hosts macro and micro organisms that break down biological waste. The same is true in actual ocean reefs.

Live Rock as the Base for Your Aquarium

Live Rock as the base for your aquarium is meant as both literal as well as figurative. It is literally the base that the live corals host on as well as the figurative base for filtration.

Live Rock Facts

  • The purple coloring seen on most live rock is coralline algae
  • Additionally, coralline algae is both beautiful as well as beneficial as it reduces nutrients pest algae would otherwise use to growth and thrive
  • You can purchase live rock to jumpstart your aquarium’s nitrification system or you can grow your own by allowing the micro organisms the develop naturally on dead rock and as a result save money
  • Real ocean live rock can instantly provide beneficial organisms to your tank obviously because it is still “live”
  • It is prone to having unwanted pest hitch hikers such as aiptasia anemones, bristle worms, fire worms, nudibranch, and more
  • Aqua-cultured rock is a good option as it has been developed in a more controlled environment and therefore is usually more free of pests while still containing plentiful beneficial organisms

Dead Rock Facts

  • Dead rock is simply rock that used to be live but has been allowed to dry and has been cleaned – no longer containing any beneficial or pest organisms
  • Starting a tank with dead rock can help minimize pest introduction to your aquarium
  • Dead rock can be cultured through what is referred to as the nitrogen cycle to develop beneficial micro organisms
  • There are are several types of dead rock available, such as Fiji and Pukani which are eal dead coral rock, and there is also rock known as Reef Saver which is man made
  • The more porous the rock the more it can host beneficial organisms
  • Pukani is known to be the most porous while the man made Reef Saver is quite dense

 

Coralline Algae

Coralline algae is a hard crust-like algae that is purple in color and grows over live rock. Some dead rock is available for sale colored to look like it is covered with coralline algae. Walt Smith 2.1 Reef Rock is one of these and is a reasonably good choice for going with dead rock and having the coralline algae look.

Another method is to seed your tank with coralline algae and/or use a booster to help accelerate growth. CaribSea Purple Up is a good accelerator. To seed your tank with coralline you can get some scrapings from another tank and add it to your aquarium. There are many ways coralline algae gets into your aquarium so seeding it may not strictly be necessary but it may help accelerate the process. ARC Reef also has some dead rock kits that come with some wet rock that has coralline algae to help accelerate the process.

How Much Live Rock Do You Need?

There really isn’t a hard and fast rule here. It’s not uncommon to hear 1 to 2 pounds per gallon. Different varieties of live rock will weigh differently due to densities of the rock. A more porous and less dense rock will be able to harbor more beneficial bacteria than a dense and solid rock. In general, more is better but there’s no need for overkill. Fiji and Pukani reef rock are pretty light and porous. Pukani being better able to flow water through it means it’s a little better and sustaining good bacteria.

If you are considering an aquascape design that would need less rock than would be ideal for your aquarium you should consider adding live rock in your sump. You could also consider a produce like MarinePure blocks, plates, or balls. This stuff is super porous and flows water through it extremely well. It’s ideal for replacing reef rock in your aquarium.

Aquascaping with Live Rock

When placing rock you’ll want to put it into your aquarium before any sand or other substrate. This will give your rock a solid footing that won’t shift. Some people add egg crate or some other material to the bottom of their aquarium to protect the glass. This isn’t a necessity but if you’re the cautious type you may want to consider it.

When aquascaping you also want to make sure that any rock you stack is secure. Use an aquarium epoxy to glue them into place. You may even want or need to build an armature with acrylic rods and drill through your rock to run the armature to ensure stability, depending on your desired design.

It’s usually easier to work with dead rock when designing an aquascape. A dead rock that is very porous, like Pukani, is ideal. It is easily chiseled and looks very natural. You can also take your time working with it since you don’t have to worry about live bacteria dying off.

In Conclusion

Starting with dead rock and culturing bacteria by cycling your tank is the best way to go but will require patience. Starting with live rock will get you going fast but you’re very likely to almost certain to have to deal with at least some hitchhiker pests. My local fish store had some Carib Sea dead rock that it cultured and sold wet. It’s a great middle ground. My experience with it went without a hitch, however it’s common for fish stores to have many pests in their systems. This obviously means there’s a high probability of still ending up with pest in your rock. My experience was good but if you come across a local fish store that either offers this service or will entertain doing this for you I suggest discussing the hitchhiker issue with them.

Starting with dead Pukani is probably the best route. You can do all of your aquascaping more easily and have a pest-free start. In general, the more live rock you have the better off you’ll be. That said, I also like adding MarinePure media to the sump to help increase the live rock volume. Get some coralline algae from a friend or ask your local fish store if they’ll scrape some off some rock they have for you to add to your tank. Use some coralline booster to help accelerate the process.

Your tank, your personality, and your needs will dictate your choices. Hopefully you’re a little more informed and can comfortably make a good decision.

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