Saltwater Tanks Demystified Part 03: Live Rock, Aquascaping, & Sand

Table of Contents

I) Introduction

Part 03 of Saltwater Aquariums Demystified has arrived!  This is going to be a long post, because there is just so much to cover.

This blog goes into much more detail than the video, so maybe start with the video and then scroll through the blog for links to all of the products you’ll need.

If you want to jump to any episode, just click on the link below.

To watch the entire vlog, just scroll down a skosh more and click play!

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1) What is Live Rock?

CaribSea Life Rock

Is there some sort of magical rock that comes alive in the saltwater aquarium hobby?  Obviously not.  Rather, live rock becomes alive once it is colonized by beneficial bacteria.

Live rock is usually made of the mineral aragonite, which is calcium carbonate.  It is the same material found in coral skeletons and snail shells.  It is highly porous, and provides a great home for nitrifying bacteria. It can be naturally made or human made.

Live rock, once colonized, acts as your primary biological filter, turning toxic ammonia into a much less toxic nitrate.

2) Function of Live Rock

There are 4 primary functions of live rock:

3) Wet vs. Dry Live Rock

Dry Live Rock- CaribSea Life Rock

This distinction is becoming less and less important, because most retailers nowadays only sell dry live rock.  But you can still find wet live rock from your LFS or certain retailers.

Here’s the difference between the two:

  • Dry live rock arrives at your doorstep completely dry, free of any pests or hitchikers (both good and bad), and with no beneficial bacteria. Dry rock is my personal preference. You will need to cycle the rock in your aquarium, but you won’t need to cure it because it likely is already free of decaying matter. 
  • Wet live rock arrives wet, usually wrapped in newspaper, may come with pests/hitchhikers, and is likely colonized with beneficial bacteria. Do not buy live rock that is pulled directly out of the reefs.  Rather, there are companies that place their rocks into saltwater tanks or a designated place in the ocean, specifically to seed with bacteria.  These companies do not pull from the reefs, thus being much more sustainable long term.

4) Source & Ecological Impact

Nature's Ocean Base Live Rock

Live rock usually comes from one of three sources:

  • Pulled directly from the reef.
  • Quarry.
  • Human made.
  1. Reef– Do not buy live rock that is pulled directly from the reef.  It destroys the reef, costs a lot to ship, has a huge carbon footprint, etc.  I don’t usually give such strong advice or opinions, but I do believe that most of us got into this hobby to protect our reefs, not destroy them.
  2. QuarryMarco Rocks is a naturally made rock that is harvested from a quarry.  The reality is that many quarries used to be underwater, thus you can find ancient sources of calcium carbonate, probably from old coral skeletons and other invertebrates.
  3. Human Made– Companies such as CaribSea & Real Reef Rock are in the business of manufacturing their own rocks, using calcium carbonate as the base.  This is a relatively new practice, so we will have to wait and see if they perform as well in the long term.  I’ve used both the CaribSea Life Rock & Real Reef Rock, and they have both been great so far.

If you really want wet live rock that has all the good and bad hitchikers, talk to your local fish store for a recommendation.  There are small companies that cure live rock in the ocean in sustainable ways that do not destroy our reefs.

5) Curing & Cycling

colorful infographic of how the nitrogen cycle works
© Marine Depot

Pretty much all dry live rock comes clean and free of decaying matter.  But, if do buy wet live rock, you may need to cure it.

Curing Live Rock– Curing live rock is the process of removing dead and decaying matter from the rock.

Let’s say you bought some wet live rock, and just didn’t put it in your tank fast enough.  Well, now you have dry live rock, that may have a lot of dead matter on it.  That is not necessarily a bad thing, but decaying matter will turn into ammonia, which is toxic for your livestock.

Brute 20 Gallon Food Grade Trash Can With Lid
Brute 20 Gallon Trash Can
Maxi-Jet 1200 Powerhead

Here’s the basics of how to cure rock:

  • Place the rock into a dark container (such as a large food grade trash can), add saltwater to 1.025 specific gravity, add a heater (78 degrees), and add a powerhead such as this Maxi-Jet 1200.
  • Test your water for ammonia and nitrite every week.  You will see the ammonia spike first as all of that dead matter starts to decompose.  Then the the nitrite will spike and the ammonia will go down.  Once the ammonia and nitrite have returned to zero, your rock is both cured and cycled.
  • During this process, which can take 6 weeks, use a gravel vacuum to siphon out the dead matter from the bottom of the trash can.  Add more saltwater to the container to cover up the rock.
  • Be sure you have a dark lid on the trash can, as any light can cause unwanted algae growth.

If you buy any of our recommended rocks below, you will only need to cycle the rock.  We will go more in depth into cycling your tank in a later blog, but cycling is the process by which beneficial bacteria colonizes your live rock, thus setting up the biological filter in your tank.

6) Shapes/Types

a) Base Rock (Foundation)

close up product shot on white background of an arch shaped human made purple reef rock
CaribSea Life Rock Shapes
Nature's Ocean Base Rock

Base rock is your standard clumpy looking rock shape.  It is ideal for most types of aquascapes.  These pieces will stack well together, and if you add a bit of cement or epoxy, will be quite secure.

The base rock shape also has tons of surface area which makes it a great biofilter.

I typically just buy a box of base rock, and then break some of the larger pieces up to give me variety when constructing my aquascapes.

b) Branching Rock

CaribSea Branching Live Rock

Branching rock comes in long, thin branches.  These can look really good when added to base rock, or you can put a pile of them in a saltwater tank to mimic the roots of a mangrove.  If you do end up with a lagoon style tank, branching rock can be a great addition to mangroves, giving schooling fish a place to hide and feel in their home environment.

c) Shelf Rock

AquaMaxx Tonga Shelf Dry Live Rock

Shelf rock is great for mounting corals.  Get creative when using shelf rock to aquascape.  You can easily place shelf rock in between two pieces of base rock, or you can use cement/epoxy to create a shelf a the edge of your scape, especially great for SPS corals that love the strong light.

d) Rubble Rock

Rubble Rock, © My First Fish Tank

When your box of live rock arrives, there will inevitably be broken pieces at the bottom.  Don’t throw them away!  These are called rubble rock, and have all sorts of uses:

7) Our Recommendations

I am going to recommend a few different types of live rock, and each for a different reason.  But, rest assured, every item on this recommended list will be sustainably sourced, not pulled from the ocean, and arrive pest free and ready to put into the tank.

a) CaribSea Life Rock

CaribSea Life Rock, © My First Fish Tank

Here’s why I like the CaribSea Life Rock:

  • Human made, sustainable.
  • Great coralline color.
  • Stacks well and quite porous.
  • Arrives with spored bacteria to help your tank cycle more quickly.
  • Hitchhiker & pest free.

b) Nature's Ocean Base Rock

Nature's Ocean Base Rock

Here’s why I like Nature’s Ocean Base Rock:

  • Super affordable.
  • Easy to purchase through Amazon.
  • Stacks well.
  • Sustainably sourced and not pulled from the reef.
  • Hitchhiker & pest free.

c) Marco Rocks

AquaMaxx Dry Live Rock by Marco Rocks

Here’s why I like Marco Rocks:

  • Affordable
  • Quarried, not pulled from the reef.
  • Super porous.
  • Stacks well.
  • Hitchhiker & pest free.

d) CaribSea Life Rock Shapes

close up product shot on white background of an arch shaped human made purple reef rock
CaribSea Life Rock Shapes

Here’s why I like the CaribSea Life Rock Shapes:

  • Arrives in unique shapes and basically completes the aquascaping process for you.
  • Human made, sustainable.
  • Great coralline color.
  • Stacks well and quite porous.
  • Arrives with spored bacteria to help your tank cycle more quickly.
  • Hitchhiker & pest free.

8) How Much Do You Need?

This totally depends on several factors:

  • What kind of scape do you want?
  • How heavily do you plan to stock your tank?
  • Is live rock your only biological filtration?
  • Do you have a sump?

A good rule of thumb is to purchase 1.5 lbs per 1 gallon of water.  I always recommend buying more than you think you need, that way you can break pieces and don’t have to worry about making mistakes.  

Yes, live rock can be expensive, but it’s not only the biological filter, it also gives off the essential aesthetic feel to your system.  You’re going to have to look at it forever, so why not get something you like, and build something beautiful.

III) Aquascaping

a) What is Aquascaping

Aquascaping is the process of adding live rock to your aquarium in both a functional and aesthetic way.

If I’m being totally honest with you, the aquascaping process is one of my least favorite parts of this hobby.  I’m never fully satisfied with how it turns out, it takes a long time to get it right, and it’s just not my strength.

But that being said, I’ve made some pretty decent scapes.  Check out this one I did on my neighbors tank.

© My First Fish Tank

Definitely one of my better jobs, I hid the seams nicely so the entire scape appears to be one solid piece.  The addition of the branching rock worked well.

Here’s a video of me scaping my SCA 120 Gallon Tank.  Not my finest work, but you can at least see my process!

b) Types of Aquascapes

The only limit to aquascaping is your creativity!  That being said, there are two primary ways to scape your tank:

  • Stacked– By far the most simple, this involves merely stacking your pieces on top of each other.  This takes little time, and is handy because you can remove the pieces whenever you need to (i.e., to catch a fish). But on the negative side, your aquascape will be more prone to toppling over, especially if you have certain invertebrates such as sea urchins and turbo snails.
  • Secured– My preferred method, to build a secure aquascape you will need to use either some sort of epoxy/glue or cement.  My two favorite items I always use are the Aquaforest Stone Fix (which is quite hard to find!  Have your LFS order you some!), and Two Little Fishies Aquastic Coralline Red Epoxy.
Aquastik Coralline Red Epoxy
Aquaforest Stone Fix Blue Based Cement
Aquaforest Stone Fix

c) How To Aquascape

If you are just doing a stacked aquascape, it couldn’t be easier.  Just stack the rock on top of each other, being sure it feels secure, and leaving enough space around the edges of the tank so you can get an algae scraper in there.


1) Breaking Live Rock

If you bought extra live rock, you’ll likely want to break up some of the larger pieces to get different shapes and sizes.  Always wear appropriate safety gear such as goggles and gloves when using any of these techniques. 

  • Drop it- some rock will easily break apart if you merely drop it onto a hard surface.  Obviously you are rolling the dice here, as you have no control as to how it breaks.
  • Use a saw- any type of saw or sawzall can be used to cut at precise points.  This method is handy when you want to create a flat foot to give the initial pieces more stability.
  • Chisel- A chisel can be a really handy tool as well. Just a quick word of caution. Sometimes you may think your piece is almost perfect, and you go in for that last chisel, and bam, the entire piece breaks apart!

2) Inside or Outside The Tank

If you are just doing a simple stacked aquascape, you can probably do all of your scaping inside the tank.  Just be extra careful not to scratch the glass or drop pieces, as a single drop can crack your tank, rendering it useless.

3) Use Cement & Epoxy

When securing your pieces together, I’d recommend using a combination of cement and epoxy.

Cement is handy, especially when you need a large amount.  Only mix small batches at a time, as it will set quite quickly.  Use a small piece of rubble rock to give a more naturally looking texture to the cement.  I would let the cement cure overnight, and even then, be careful when lifting and moving it, as the pieces can still break apart.

Epoxy is great for smaller pieces, but you have to remember that epoxy is not meant to “stick” the pieces together.  Epoxy works by building a structure around the two joining pieces. Once the epoxy hardens, then it will have secured the pieces together.  So don’t just use a little bit and think you can stick pieces together like glue. Epoxy is also really handy for attaching any pieces after you’ve added water, as it is reef safe and can cure while wet.  

Be sure to use gloves, as it can be a pain to get off your hands! And buy extra epoxy, because you’ll be surprised at how much you go through!  You can always return the extra!

d) Tips & Tricks

1) Use A Cardboard Mockup

© My First Fish Tank

I’d highly recommend precisely measuring the inside dimensions of your tank, and then cutting out two pieces of cardboard to match.  The cardboard will not only allow you to accurately scape your tank, it will also protect your table top from scratching.

2) Rule of 3rds

By Tadrart01.JPG: Pir6monderivative work: Teeks99 (talk) - Tadrart01.JPG, CC BY-SA 3.0,

For the rule of 3rds, you take an image, and you place two horizontal lines and two vertical lines, breaking it up into nine equal parts.

The rule of thirds basically says that an image, movie, aquascape… is more visually striking if the subject is placed at the intersections of the lines, rather than in the center.

Obviously this is an aesthetic principal, so is open to personal preferences.  But I’ve found this rule helpful when designing aquacapes.

I will often use blue tape and place two horizontal and two vertical lines on the cardboard mockup.  I will then try to arrange any pillars or focal points to be at the intersections of the lines.

3) Flow Patterns

© My First Fish Tank

This is a common beginner mistake, just because if you’ve never seen a wavemaker in action, how could you understand how flow works in your tank?

Where you intend to place a wavemaker (or the return nozzles) matters when aquascaping.  In the image above, the wavemaker pushes water toward the opposing end of the tank, and then circles down toward the bottom as it returns.  I have a second wavemaker that does the same thing in the rear of the aquascape.

So, if you build your scape in such a way that blocks a natural flow pattern, you will inevitably have problems with dead areas in your tank.  Why does this matter?  Because dead areas will be a dumping ground for detritus, uneaten food, and fish waste.  It will cause your ammonia to spike, and will require more maintenance from you over time.

So plan ahead, and build your scape with your flow pattern in mind.

4) Light Penetration

Kessil A80
Reef Breeders Photon Lights

This is totally dependent on the type of light fixture you purchase.  If you get a puck type light, where all of the LEDs are clustered around a single point, you will have to be more careful where you place the rocks in your aquascape.  But if you have a long light fixture where the LEDs are spread out evenly, this will be less of an issue.

Let’s take the Kessil A80s pictured above.  If you were to place a large rock near the fixture, you would likely get a ton of intensity on top of the rock, but would get shadows below.

But if you went with the Reef Breeders on the right, the LED’s are spread out along the entire fixture so the chance of shadows is much less.

5) Space

Sort of an obvious one, but be sure to leave enough space between your aquascape and the glass so you can get a magnetic algae scraper in there!

6) Hiding the Seams

© My First Fish Tank

The above scape is composed of five pieces of base rock, plus several pieces of branching rock. After the cement had set for a day I coated the seams with either the glue or epoxy, and quickly added pieces of rubble rock.  The result is what appears to be a seamless aquascape. 

I’d recommend either of the products below for this task, and trust me, you will be happy with the results.

Extra Thick Superglue

7) Stability & Feet

© My First Fish Tank

I like to aquascape in such a way that there is the smallest amount of surface area possible between the rock and glass.  If you just take a piece of rock and place it horizontally on the glass, that is a large area where there will be no flow, and detritus can build up over time.

So I like to scape so as to minimize the contact between the rock and the glass by placing pieces vertically whenever possible.  You just need to make sure the piece is stable, and if it isn’t, either prop another rock against it, or use a saw to flatten it out.

IV) Live Sand

A) What is Live Sand

Fiji pink sand in 20 lb bag with close up of grain size
Live Sand

Live sand is usually made out of the same material as live rock, namely aragonite (calcium carbonate). 

Live sand comes in either a wet form or a dry form.  Wet live sand is already pre-populated with beneficial bacteria, not only making it truly alive, but helping cycle your tank more quickly.

Dry live sand has no beneficial bacteria, so it is not technically “alive” when it arrives at your home.  You will need to seed it and allow the beneficial bacteria time to colonize.

Sand is not an essential part of a saltwater setup.  A lot of hobbyists really like the look of a bare bottom tank, and I get it.  I personally prefer sand in my display tanks, not only because I find it more aesthetically pleasing, but because it increases the size and capacity of the biological filter. Although I do not run sand in my quarantine tanks for maintenance and medication purposes.

B) Function of Live Sand

There are three primary functions of a live sandbed:

  • Biofiltration– just like other ceramic biomedia and live rock, sand provides surface area for beneficial bacteria to colonize.
  • Aesthetics– I just think it looks nicer!
  • Livestock– Various types of livestock need a sandbed for their survival, whether that is for food or for hiding. Some examples are sand sifting starfish, cerith snails, and sand sifting gobies.

C) Types of Sandbeds

There are two types of sandbeds: deep and shallow.

  • Shallow Sandbed– Anything 2″ or under, a shallow sandbed is my preference.  It is deep enough to provide a home and food for most livestock, but not too deep as to possibly cause gas pockets. The entire sandbed will receive oxygen, so will provide a good home for aerobic nitrifying bacteria.
  • Deep Sandbed– 4″-6″ in depth, the entire point of a deep sandbed is to provide a place for anaerobic bacteria to grow.  These bacteria turn nitrate into nitrogen gas, helping to remove nitrate from your tank.  But if not done properly, they can become a nutrient trap, and contain large pockets of unhealthy gas that could hurt your livestock.  If you research deep sand beds more, be sure you get an adequate clean up crew that will constantly aerate and sift the sandbed.

D) Grain Sizes

Fiji pink sand in 20 lb bag with close up of grain size
wet live sand for saltwater aquariums close up shot of 10 pound bag

We generally break grain sizes down into three categories:

  • Sugar Fine– 0.25mm-1mm- Great for low flow tanks.  In high flow tanks, may blow around and cause a sand storm.
  • Special Grade– 1mm-2mm- My preference.  Heavy enough not to cause sandstorms, but not too big to trap detritus.
  • Coarse– 3mm-5mm- Usually crushed coral, I’ve never used this.

E) Colors

White & Pink

You pretty much have three choices: white, white with a little bit of pink, and black… that’s it!

F) Our Live Sand Recommendations

We have three favorites which we’ll list below, but really anything from the CaribSea Arag-Alive product line is great.

1) CaribSea Arag-Alive Special Grade
wet live sand for saltwater aquariums close up shot of 10 pound bag
Special Grade 1-2mm

Special Grade is my current favorite, primarily because the larger grain size really tamps down on any sand storms.  My 120 gallon is a medium-high flow tank, and I fear that the Fiji Pink sand would blow around a bit too much.

Fiji pink sand in 20 lb bag with close up of grain size
Fiji Pink 0.5-1.5mm

Fiji Pink is my go-to in any low flow tank like the Innovative Marine Nuvo Encore featured in this 10-part video series.  The light pink hue is lovely under the lights, and the small grain size means it doesn’t trap a lot of detritus.

3) CaribSea Arag-Alive Hawaiian Black
hawaiian black sand in 20 lb bag with close up of grain size
Hawaiian Black 0.25-3.5mm

I’ve used Hawaiian Black before in my Red Sea Reefer 170, and I loved the contrast in the tank.  Even though the packaging says the grain size goes up to 3.5mm, I found that the majority or the sand was closer to Special Grade.

F) Common Questions

1) How Much Sand Do You Need

If you want a shallow sandbed under 2″ in depth, a good rule of thumb is to purchase 1lb of live sand for every 1.5-2 gallons of water.

If you want some help getting the right amount, check out this Sandbed Calculator.

2) Can I Use Beach Sand?

Potentially yes, but there are two caveats:

  • Laws– Especially here in the United States, there are federal, state, and local laws that may prohibit or limit the collection of live sand.  So do your due diligence first before collecting sand.
  • Clean Source- If it is legal to collect, then choose a clean portion of the beach, not near any runoff.  Sand often has plastics, oils, and other metals that may not be good for you tank.  Even if you find a clean portion, I would rinse this sand out several times before adding it to your tank.
3) How Do I Maintain A Sandbed?
  • Water Changes– use a gravel siphon during your waterchanges to gently remove detritus from your sandbed.  I’d recommend pinching the flexible tubing from time to time, as you can end up siphoning out the sand itself, and that is certainly not the goal.
  • Clean Up Crew– There are a lot of creatures out there that will help keep your sandbed aerated, and help consume organic matter.  Some good options are cerith snails, nassarius snails, conches, sand sifting starfish, and sand sifting gobies.

IV) Episode 04: Water Chemistry, RO/DI, & Salt Mixes

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