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Presented by Charles & Linda Raabe
Mactan Island, The Philippines
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  Besides acting as a major component of our filtration, Live rock, Base rock and sand also provides our tanks with some diversity of life forms. A few thoughts of my own on this subject.

   For the sake of using correct terminology, Live rock is NOT bare rock that has some filtering bacteria on it, I don't care who or how many people continue to use the term "live" for what should be correctly called base rock. To state that a base rock is "alive" just because it has had time in a tank to develop some bacteria on it is misleading, if that was the case, then I have "live" glass, and "live" plastic in my tank. As the filtering bacteria will grow on anything you put in the water. 


 Photo by Charles Raabe
This is what Live Rock, right out of the ocean looks like.

(A). LIVE ROCK = Calcium carbonate or Lava based rock that has been colonized by a multitude of life forms including, but not limited to: corals, sponges, algae, inverts, worms and of course bacteria which forms a habitat unto its own. This type of habitat forms the foundation of all tropical reefs. 


Base rock being colonized by coralline algae

MAKE YOUR OWN ROCKS
( Click above link to learn more )

(B). BASE ROCK = Calcium carbonate or Lava rock that is void of all life forms and is primarily used as a "base" to put live rock or corals on top of it. NOTE: If the base rock has been in an established tank, then it will most likely have the filtering bacterias already on it. I do not consider this type of rock to be correctly termed as live rock.

   IN REALITY :  I seriously doubt that we, as a hobby, will ever be able to maintain all of the life that is found on and within live rock as found coming right out of the ocean. Having bought live rock in the U.S. I am quite familiar with the life forms that get lucky enough or are hardy enough to survive having been shipped from the other side of the planet as well as having gone through a curing process, which will happen to any rock whether you yourself buy it as such or put uncured rock into your system. It will always have some die off regardless.
   I would not be concerned at all with getting live rock in the same condition as it is found in nature, simply because once all that life is put into the relatively small and confined space of our aquariums, it will in short order be stripped down of most of its life forms. Only the most hardiest of species or those species that your tank's conditions suit, will end up as the dominant life forms on the rock.
   In nature, any herbivore or predator only takes a nip or bite here and there and moves on, something the "rock" can easily recover from quickly. But when those herbivores and predators only have ten or twenty rocks at their disposal and all day to snack on it within a confined space, those rocks are quickly wiped clean of all life forms except those that the herbivores and predators do not naturally eat. Which leads me to a point often debated. Can you take bare base rock and put it in with live rock to turn the base rock into live rock? Yes and No....No because the base rock will never become as the live rock was found in nature. Yes because those same life forms that are left behind untouched by the herbivores and predators will spread to the base rock, making the base rock look exactly as what the live rock has been reduced to.
   I say all of this simply because I have daily access to all the natural live rock one could ever dream of and have for the first few years of my system been removing a few rocks and replacing with fresh rock right off of the reefs. I can say without a doubt, that within two months or less, that wonderfully fresh and full of life live rock will end up looking just as "bare" as all the other rocks that have been in my system for a few years. The only way that I can maintain any diversity of life within my system is by the constant swapping out of live rock and sand to introduce more life that has been eaten or could not survive my tank's conditions. I have tried for over a year to find a balance between herbivores and predators to no avail, if the herbivores are restricted, not all algae species will grow in the same manner as they do in the wild, and I end up with one or two species out pacing all others and dominating the tank and threatening the corals with being smothered. Even with all predators removed, such as wrasses and crabs, the vast multitudes of small inverts populations either crash or explode to where only a few species dominate all else. Sad to say, I seriously doubt we could ever prevent this from happening no matter how much one would experiment with herbivore / predator species and population densitys. Its just not going to happen. Try as I may.
  As such,  I believe it is imperative that any true reef aquarium system be comprised of multiple aquariums set up as refugiums for the various habitats that make a coral reef possible. To try and contain all within a single reef aquarium will only result in frustrated failure as noted above.  I strongly recommend the use of filamentous algae "filters", sea grass habitat refugiums and macro algae refugiums be tied into the main coral display aquarium. Doing so will allow a much higher degree of biodiversity to be maintained, which will in turn, maintain your coral reef display.
(C). SAND = The same terms and descriptions can be applied to Live Sand and Base Sand.

 The use of and care of Live Rock :

There are two ways that you can introduce live rock into your tank.

(A). Buy all your live rock and base rock at one time when you set up your tank and let it cure during your tank's initial cycle period. This is the most common method. But one that could endanger the life forms that you paid for, if the live rock is nothing more than coralline encrusted rock, then I would not be worried about it then.

   Photo by Charles Raabe   Photo by Charles Raabe
              Fungal and Bacterial mats decaying dead organics on live rock

(B). Buy your base rock only when you set up your tank and allow it to become part of the filtration as it grows bacterias on it during the initial cycle period. This method is what I believe to be a better option. Once your tank has cycled and is ready for the addition of live rock. I would treat each piece of rock just as if it was a fish addition. A short curing (quarantine) period of letting it sit in a small tank or bucket while doing frequent if not daily water changes to control ammonia levels is an effective method of keeping all those life forms that you paid for alive. It is also a good chance to inspect the rock for any unwanted hitchhikers such as crabs or mantis shrimp, it is far easier to remove these creatures while the rock is not in your main tank.

 Live Rock as a Biological Filter : Hit or Myth?  -  " One of the tried and true methods of providing biological filtration is by the use of "live rock." This method has been suggested by virtually every author "

  A note for those setting up Fish only with Live Rock (FOWLR) aquariums : Do not waste your money on doing so. Since such an aquarium is going to be used to keep a variety of fish, it is a fair bet that a good many of the fish you wish to have will find the live rock to be a great source of food and will strip the life off of the live rock and turn your six dollars a pound live rock into two dollars a pound base rock in a very short time. You will get the same beneficial filtering capacity from base rock as you would from live rock. For it to do so, all rock needs to be is a surface area for the biofilm (bacteria), which base rock is quite capable of providing. It makes no sense to me to fill a tank with hundreds of dollars of live rock only to watch a wrasse or an angelfish take bites out of it and come away spitting sand. If you want that much live rock in your tank, then you will have to stick with reef safe fish, and if you do that, you might as well make a full blown reef tank and enjoy all the life to be found in/on live rock. For fish only systems, using base rock for the majority of your rock will save you alot of grief and money. You can of course add one or two pieces of live rock just to get some coralline algae to spread and cover the base rock, but that can be done also by just getting some scrapings off of a tank that has coralline growing on their glass and just sprinkle it into your tank. Save your money and some live rock and enjoy your fish.


Lava Based Rock - I would not recommend the use of lava based rock be used with the intention of it providing a suitable environment for the colonization of marine life. Being a silicate based rock, the crystalline make up of such rock is far too jagged or sharp for most life forms. That and it tends to be a great deal less porous than the calcium carbonate based rocks. There is also the concern that being lava, it could contain other elements that within an enclosed system could pose toxic concerns.

Major Chemical Elements Forming Igneous (Lava) Rocks

Illustration by J. Johnson  -  Glossary of volcanoe terms

 
   There is alot of debate on the depths of sand beds but will post my opinions on their use.

  I would recommend an Argonite sand with sugar sized grain or smaller.. This sized grain is best suited for the most common inhabitants of our tanks, it provides a correct home for fish that use it as a burrow, or a hiding/sleeping place such as the wrasses and gobys. It also is the correct environment for all the sand dwelling worms and other inverts.

It also provides more surface area for the beneficial filtering bacterias to grow on.

  For those unable to, or unwilling to set up a live deep sand bed, a shallow "dead" sand bed still provides a great amount of surface area for bacteria to live upon. Such shallow sand beds can provide for the bulk of bacterial "filtering" for both the conversion of ammonia to nitrates, as well as for denitrification purposes. Both processes can and do occur on the sand's oxygen rich surface layer.  Shallow sandbeds that are not "live" will need to be disturbed once a month to prevent the bacteria from cementing the sand grains together and forming brick hard clumps. Such clumping of the sand prevents any water / gas movement, however small, from happening and could lead to the build up of noxious compounds. The "disturbance" can be simply you swishing the sand around with your hand or siphon cleaning it. The use of a "gravel" siphon cleaner can be used on sand if the siphon hose (output end) is kept raised higher than normal to slow down the force of the siphon, something you will just have to get a feel for to prevent siphoning out your sand. I must stress that this is for shallow (1-2 inches deep) dead, sandbeds. You would never want to disturb a live deep sand bed in any manner.

  How to move an established live sandbed :  Please see this forum discussion .

  It also just looks more natural in my opinion.

  NOTE: A good method of introducing a sand bed during set up is to just buy dry dead sand and once your initial cycle has completed, then add another thin layer of truly live sand on top of it. By doing so, the live sand will seed the dead sand and in due time, the entire sand bed will be considered "live".

  As usual with any given subject within this hobby, there is a lot of mythinformation concerning deep sand beds. The most popular myth that still abounds to this day is that a deep sand bed is doomed to fail and will become a nutrient sink releasing all kinds of toxins into your tank. Of course there can be problems with deep sand beds, but it is not due to anything inherent about such sand beds and is instead caused by not properly setting it up or correctly maintaining it. A case of blaming the sanded and not ourselves. With everything, once you understand the biology, the myths become apparent as nothing more than poor science and incorrect observations. Hopefully the following links will dispel the garbage that is thought of as being true.

How SandBeds Really Work  -  "  If aquaria are artificial ecosystems, however, the component that is least artificial is the sand bed. This part of a reef aquarium, with little input from the aquarist, functions much as do the sandy areas near a real reef. That functionality is due to a rather complex interaction of physical and biological factors, but most of those interactions are unseen, and, I think, unappreciated by the average aquarist. "

The Importance of Deep Sand  (how to set up and maintain a deep sand bed)  -  " These beds provide three things. First, they provide a place for processing and exporting some dissolved nutrients. Second, they provide a place to recycle detritus, excess foods, animal feces and other particulate material into usable forms. Finally, they provide a food source for many reef animals. Let's look at each of these functions. "

How A Deep Sand Bed Can Produce Food For Reef Inhabitants.  - " Our reef aquaria are what a biologist might call "microcosms," or small copies of the real habitat. These contain the appropriate substrata, animals, and algae to be analogues of the real world. "

What Lives in Live Sand  -  " Two basic organism groups are found in reef sand, both in an aquarium and in nature. “Meiofauna” live on the individual sand grains or in the thin films of water between the grains. “Infauna” live within the sediment, but generally displace it in their activities. "

Some visual aides (photos) of sand bed water interactions :  Photo 1   Photo 2   Photo 3   Photo 4  

   From time to time, I collect a few pounds of live sand from the ocean to swap out with my tank's sand bed in an attempt  to keep the sand infauna populations  as abundant and diverse as possible. After just a few times of looking at small quantities of sand, it quickly became apparent to me that the life found living in such substrates are extremely important to the health of the sand bed. Having found a great deal of life forms, most of which are just too small for me to photograph even with a dissecting scope, I thought it would be of interest to show those that I can photograph.



  From ciliates, foraminiferans, snails, worms, protozoa, copepods, amphipods, isopods, and a great many other creatures that I can not identify, all make for a very interesting and diverse habitat, one that we do not actually see often, if at all. I will try to provide identifications when possible.
  A few observations made : My first look at a sample of "wild" sand made a few things quite obvious. For one, the sand grains are extremely small. Having observed the size of the animals that live in such substrates, even the grains that we would think of as being mud were in comparison with the animals, the size of boulders. The typical sand grains we use in our aquariums must be to them, like having houses stacked on each other. Secondly, there is a lot of organics present. All of which is the foundation of the food web within this tiny world. Having this world within our aquariums, if set up and stocked correctly, would be of great benefit to our aquariums, by not only providing nutrient processing, but by having all those myriad of life forms adding themselves, as food, to our other larger life forms that we keep.
  Not only are the residents of the sand bed visible when under a scope, but there are a great many remnants of other larger animals to be found, from small sea urchin spines, cast off exoskeletons, and an endless array of bits and pieces of animals that I could not even guess at as to what left them behind.
 
A few examples of foraminiferans :  This group of animals forms the bulk of animal remains that I could see.
Photo by Charles Raabe   Photo by Charles Raabe   Photo by Charles Raabe

Worm examples: The largest and most easily to be seen, Some species, as adults, remain near microscopic, while others are but juveniles of larger worm species. Some are detrivores, while others are the predators.  
Photo by Charles Raabe   Photo by Charles Raabe   Photo by Charles Raabe

Examples of some of the more unusual finds. All photos taken at my scopes and cameras max zoom capability.
Photo by Charles Raabe   Photo by Charles Raabe   Photo by Charles Raabe
Photo by Charles Raabe   Photo by Charles Raabe   Photo by Charles Raabe

For more photos of animals found living in, on and above the sand beds, please see HERE.


  Reef Collecting  -  For those of you who can collect from the ocean

 Sand Bed Calculator  - Determine how many pounds of sand your aquarium will need per a given depth.

SAND / REEF INFAUNA SOURCES :
 Since live sand is not always available and the fact that a deep sand bed (dsb) is required to be "live", the following suppliers are a good source for getting the needed life forms to create a healthy living sand bed when using "dead" sand such as any of the play sands that can be purchased at local garden centers. These are strictly sources and not an endorsement by me. Do note that if you see any hermit crabs or sand sifting starfish included in any of the kits, do not buy them since such animals are detrimental to not only a sand bed but to a reef tank as a whole.

 Essential Live Feeds (copepods)   Bill's Reef  ( bristle & spaghetti worms )   Inland Aquatics  ( Detrivore kits )
  Indo Pacific Sea Farms  ( Many choices )





CRUSHED CORAL SUBSTRATES -  Since this product is still pushed off onto new hobbyists and becomes a constant source of discussion and concern, I am going to try and save myself from having to constantly address this product by placing what I know of it within this page, at the least, it will save me from having to type this same information again and again.
   It is extremely common for a new hobbyist when purchasing a new setup at a local fish store to be sold crushed coral as a substrate, only to find out later from other hobbyists who have used this substrate that they now need to remove the crushed coral and replace it with some actual sand. I suppose this is not so much the store's fault as they do need to have a substrate available to include with new aquarium set ups. Being that the only criteria for a substrate is one of being nice and white, all of the other important concerns are not given much thought, if any. Hopefully, both hobbyists and store establishments will start to realize that within the quest to provide a proper habitat for our aquatic pets, the substrates provided must be taken into account also.
  
As I have yet to hear of a single good reason to use crushed coral, I can only list what I know of it being a bad choice as follows - 

1 - I can think of no animals other than worms that would use such a large grained habitat to live in. Any fish that burrow or sleep in the sand such as most wrasse and goby species will not do well and most likely will end up with alot of abrasions, which only opens them up to infections.

2 - Surface area for an aerobic bio filter, Nope, you get less surface area with crushed coral. Which could be important since only the surface of the "sand" bed will have enough oxygen to keep a bio filter going, down in the bed, it will be stagnant, but the grains will still be large enough that anaerobic bacteria will not be able to perform their function, In short, a crushed coral bed not only provides less bio filter, it also denies the benefit of having denitrification occur deeper down as you would get with actual "sand".  In other words, it sucks at doing what it is claimed to be, which is a substrate.

3 - Crushed coral is a maintenance pain in the arse, being so large grained, any and all "crud" can easily get down deep and it just lays there and rots away into ammonia. Even if there was a worm population living in the gravel, they would never be able to process the amounts generated by a normal system. Which means, you have to either siphon clean the gravel on a regular basis or stir it all up and allow your filter pads to try and trap it, then you have to constantly clean the filter pads, and during all of that, you will most likely still face water quality issues that you need not to by using "real" sand.

4 - Its just not natural and looks like crap...lol, I have yet to see a natural habitat that is made up of crushed coral. Its either rock or sand and/or a combination of the two. Which is why "they" have to actually MAKE crushed coral, if it was so natural, why is it made and not just scooped up out of the oceans like other sands are? Yes, there are blends made to include sea shells, rock fragments and such, but the only time you are going to see that type of habitat is if you are standing on a Florida beach in just enough water to get your ankles wet, not a place you will likely find a reef, or fish for that matter. 

 Applications of Sand in Reef Aquaria  -  " It is apparent from the simple experiments done using sand, sand and calcifying algae, and coral fragments that the dissolution of carbonate sediments is not adequate to maintain the calcium or carbonate alkalinity of aquariums housing even very low numbers of calcifying organisms. "

  Besides not taking into account all of the above, this product is also touted as providing calcium and pH buffering through it dissolving slowly in our aquarium water. I find this incredible for the following reasons -

   Calcium carbonate will not dissolve in your tank, it could, but I will get to that one single possibility later... All of what I know of and found about this subject came from one single page, and if you wish to dig deeper or dont want to believe me. Here is THE PAGE.
What is calcium carbonate? Also known as limestone, calcite, argonite, chalk and marble. - It is not a single item actually but is a compound ( CaCO3 )
Calcium carbonate shares the typical properties of other carbonates. Notably:
  1. it reacts with strong acids, releasing carbon dioxide:
    CaCO3 + 2HCl ? CaCl2 + CO2 + H2O
  2. it releases carbon dioxide on heating (to above 825 °C in the case of CaCO3), to form calcium oxide, commonly called burnt lime:
    CaCO3 ? CaO + CO2
Calcium carbonate will react with water that is saturated with carbon dioxide (CO2) to form the soluble calcium bicarbonate. 
CaCO3 + CO2 + H2O ? Ca(HCO3)2
  Note the above where it states THE SOLUBLE calcium BIcarbonate, this is where we get the buffering effect to stabalize our pH.  Also note that it takes an acid (very low pH) to effect this reaction.  NOT something that is going to happen in our tanks with one possible exception. For those of us who use a deep sand bed there are bacterial processes taking place that do produce acids, those acid in such a low flow area can drop the pH level low enough to start releasing calcium bicarbonate (dissolving argonite based sands) but it will not be enough for you to be able to detect any benefit from it doing so. So to say that such sands can buffer your aqurium water is misleading and incorrect. If this myth was true, there would be no reason to use calcium reactors that force the dissolution of calcium carbonate based media through the use of CO2 injection.


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