LIVE SAND AQUARIUMS
A RETROSPECTIVE ON THE DIRECTION OF OUR HOBBY
When I first started in this hobby the biggest challenge was just keeping the fish alive since ammonia was much more toxic in the higher pH of the marine aquarium. Then George Smit applied the technology of waste water systems, and introduced the trickle or wet/dry filter. This was a great improvement over under gravel filters and allowed us to keep many more delicate species alive for a longer time. Water changes kept nitrates manageable, and UV sterilizers killed all those unknown "bugs" that made the fish sick
I recently thumbed through a marine aquarium book from the seventies*, it had a very interesting comment and I quote " A sterile tank is much easier to maintain than one containing living creatures other than fishes." It is interesting to note that in the same paragraph Mr. Lee Chin Eng and his natural tank with live rock and live sand is mentioned, but the aquarist was told " Just how long such tanks remain a thing of beauty is not too clear..." We knew exactly what was in our tanks back then two types of "good" bacteria and our fish. All was fine in the world until we saw that bubble coral or anemone in our dealers tanks. Now this was a new challenge could invertebrates be kept alive in the average hobbyist tank or did they need something unknown that only the vastness of the ocean can provide.
Three things became available in the mid-eighties which greatly enhanced our hobby; better lighting systems, live rock, and protein skimming all became very popular. Thus the mini-reef was born. Lots of small refinements came about in the proceeding years. Things such as ozone came in and out of fashion. Many new products hit the market; pH meters, redox controllers, even computers that could run our tanks for us. Saltwater aquariums looked more like nuclear submarines than the fish tanks they started out to be. Recently they have simplified a little with the berlin style of filtration. Yet there are new gadgets coming on the market everyday. It would be easy to spend well over $10,000 just to keep a piece of coral alive. And there is still a lot of maintenance, a lot of testing which needs to be done, and a plethora of additives to keep everything happy.
The hobby sure has come a long way. I remember another book I had showing an aquarium with a few invertebrates and a heavy growth of hair algae which was the sign of a healthy tank (as opposed to slime algae) and was beautiful to watch as it swayed in the current. How many would-be reef tank owners still feel this way about their hair algae tanks. A few years ago a number of articles showed up in different magazines and newsletters showing pictures of aquariums full of some of the most difficult to keep stony corals growing like mad, and with little or no filtration.
While we were struggling professor Jaubert had
apparently been doing the impossible for over ten years, using "live
sand" filtration. So why does this live sand filter work so well? How
do we use it in our aquariums? What about all of our fancy gadgets and
equipment do we need it or should we put it on a table and call it modern
art? Lets look at it step by step. As was mentioned at the beginning
"live sand" is a different philosophy on maintaining saltwater aquariums.
The emphasis is not having a miniature water treatment plant but on
creating a miniature balanced ecosystem.
The earth was created as a balanced ecosystem, yet we can see the effects of man on that balance, mostly in the negative sense. When our reef tank turns into a hair algae tank it is attempting to reach a balance. The fact that it is not the balance we desire is simply the result of not creating the proper conditions to get the results we wanted.
The earth was created as a balanced ecosystem, yet we can see the effects of man on that balance, mostly in the negative sense. When our reef tank turns into a hair algae tank it is attempting to reach a balance. The fact that it is not the balance we desire is simply the result of not creating the proper conditions to get the results we wanted. It's like planting an apple tree and expecting oranges, its not going to happen. So we try to artificially force our tanks into the balance that we want.
A good example is the dosing of kalkwasser. Not that this is a bad thing in fact some of the most spectacular tanks I have seen relied heavily on calcium replenishment but I ask you what would happen if we didn't continue with it? Could we maintain our corals growth and heath? The obvious answer is no. But what if there was a system that could reach a balance very similar to that of the ocean. How much easier would it be to maintain? I truly believe because of the evidence reported, and in experiments of my own that "live sand " is able to maintain a balance much closer to that found in nature. "But why?" You may ask and what is the best way to set up and maintain this type of system? I hope to answer this in the balance of this article.
We all know about or have heard of the nitrogen cycle that is necessary to remove the ammonia that builds up in our ecosystems. In conventional reef aquaria this takes place in the trickle filter or on the live rock in Berlin type tanks. Now I don't know about you but I see more than just ammonia coming out of my fish, there's chunky stuff to. Plus corals shed slime and other organics into our aquarium. So what do we do with this stuff we commonly call detritus? Remember that the reef is relatively nutrient poor so many animals have adapted to utilize any available organic matter. It goes to reason that if we provide a home for these animals then they can do the work for us. What type of animals have adapted to use this food source. Plenty, isopods, copepods , worms, crustaceans, echinoderms and a variety of other creepy crawlies love this stuff. Only one problem most reef fish love to eat these animals. So one purpose of the sand bed is to provide a safe home for the small animals which actually filter out the detritus. The animals in turn stir and aerate the sand bed. The wastes of these animals are deposited in the sand bed. There they are further broken down, by bacterial action, into basic elements and molecules such as nitrogen, water, carbon dioxide ect.
What about pH, calcium, and alkalinity levels? Most biological activities in the aquarium produce acids, this leads to the lowering of alkalinity and pH levels. Plus it is common knowledge that corals remove calcium from the water. In a conventional aquarium maintaining alkalinity, pH, and calcium levels is a tricky balance. Kalkwasser has become the most popular way of replenishing lost calcium. If no kalkwasser additions are made, over time the calcium levels drop due to utilization by animals and precipitation. Carbonate levels also drop from buffering the acids produced by biological activity.. With the loss of buffer the pH starts to fall below that of natural seawater. There is no longer enough calcium for the corals to maintain their rate of calcification, and they go down hill. Conversely if too much kalkwasser is added, the calcium combines with the carbonate and precipitates out of solution, with the same results of lower alkalinity and in time lower pH.
This is the reason that kalkwasser must be dripped in slowly for it to be of any use. Most or all water evaporated must be replaced by kalkwasser in conventional aquariums to maintain a calcium level equivalent to what is found in nature. Think about this a moment we treat our aquarium as a sick patient that must be hooked to a I.V. to survive. is there any dosing on the reef? No. So again this is an artificial balance that we are trying to maintain.
Aragonite sand should be used in the "live sand " filter. It is a fairly rare form of calcium carbonate mixed with other elements The most common places it is found is in ancient sea beds where it has been deposited by animals and plants. The skeletal remains of coral, tube worms, and calcifying algae are all sources of aragonite. Some of the best aragonite I have seen is found in Florida and is mined by a company called Carib Sea. Their Sea Floor Special Grade Reef Sand (product number 00050 or 00020) is made entirely of an aragonite which is stable at a pH of 8.2-8.4, the range in which we wish to maintain in our aquariums. It is graded to approximately 3 mm, the perfect size for the sand bed. The acids produced by biological activity are primarily formed in the sand bed, where they are neutralized by the buffer capacity of the aragonite. One result is the formation of CO2 in the sand. Because this type of aragonite begins to dissolve when the pH drops below 8-8.2 the lowering of the pH by the Carbon Dioxide in the sand releases the minerals trapped in the aragonite; calcium, carbonates, borates, magnesium, strontium and others that where laid down by animals in the seas long ago. These are then diffused into our aquarium to be used by the animals that we keep. This is similar to the principle of a calcium reactor, but it is carried out in a more natural way.
Because the balance reached in the aquarium is one dictated by the laws of nature, and the one that our animals are already adapted to, there is less of a need to add calcium. In fact to much ionic calcium may actually be detrimental to the continued balance, in that the excess calcium precipitates out with carbonates, and in some cases can solidify the sand bed with growths of calcite crystals. However this only occurs if one tries to maintain a pH and calcium level higher than that which is chemically stable in the marine environment we are trying to duplicate.
Now how do we use these facts to help us to maintain our aquariums. To what specification do we built our sand filter. These questions have of late sparked a lot of controversy. People have many different ideas on the best way to duplicate what exists in nature. This is understandable since it is impossible to duplicate the exact environment found in nature. To get the most up to date information I went to the source Professor Jaubert of the Museum of Oceanography in Monaco. In 1995 Louisville Kentucky hosted MACNA 7. The keynote speaker was Professor Jaubert. He gave a very interesting presentation describing the research he was doing on coral reef calcification and the effects on our global environment.
Part of his research deals with the effects calcification of corals and the utilization of carbon has on the greenhouse gas carbon dioxide and global warming. Since many of the coral reefs around the world are threatened, the loss of these calcium carbonate factories may be attributing to the greenhouse effect. How's that for a reason to stop polluting the reefs. To accomplish his work he needs vast amounts of live coral on which to experiment. He does not grow coral for profit or fun, but to research on. Much of the research with the end result of the death of the specimens used. It would be completely impractical and unethical to remove large amounts of corals from the wild. Due to the nature of his experiments he needs small healthy specimens of a variety of small polyp stony corals. He has to grow them unattached as little coral balls, so that their skeletons do not interfere with his readings. These are then placed in special equipment that monitors the respiration and mineral utilization of the corals. So what does all this mean to us? It means that Professor Jaubert has designed a system of filtration that he uses to grow lots of coral. We can adapt it for use in our aquariums.
Jaubert's tanks use a one inch open water space covered with 3-4 inches of 3 mm aragonite sand. This grain size is of great importance since it allows for the proper diffusion which makes this type of filtration work. Jaubert brought out that the most important aspect of this type of filtration is diffusion. Diffusion is not a thought that we usually have regarding our aquariums. In conventional aquariums every drop of water needs to be in constant motion, whereas in a "live sand" tank only the main water is circulated. Diffusion can best be described as taking a large vessel of water with no circulation and placing some ink in one spot. In time the ink will be evenly spread out. Many other directions have been given in hobbyist magazines as to how to use "live sand" most in my opinion do not work as well as what has been proposed by Jaubert.
Some hobbyist just throw a thick layer of live sand on the bottom of the aquarium. However this may lead to problems with water quality and algae, because of the high organic and phosphate levels found in some live sand, and the dead areas that are formed. I have heard of some horror stories using this method. Much of the live sand on the market is much to small to allow the needed diffusion. Pure "live sand " straight from the ocean is already full of organics, and shipping and handling kills many of the beneficial animals living in it. Placing a hundred pounds or so of this material in our aquarium can have disastrous effects. Another interesting thing I learned from Jaubert was that he usually does not use a layer of screen in the middle of the sand bed. The main reason for the use of the screen is to keep fish from digging deep into the sand bed and disturbing the anoxic or low oxygen areas. But a number of layers of screen may block worms and other smaller creatures from tunneling down into the lower layers. This is some thing which is necessary to keep the sand oxygenated and allow for diffusion, which is the life and breath of the sand bed. To help with the diffusion as much of the sand as possible needs to be left uncovered. What is needed is a material which will allow small animals and sand grains through, but will stop large animals from reaching the plenum. It has also become popular to use sand sifting animals, such as watchmen gobies, in an attempt to keep the sand bed clean. However, I have found much better results by letting the smaller worms and other animals keep the bed clean. Sand sifting fish may in fact be eating many of the smaller animals we need to keep the sand bed healthy.
Another point of confusion seems to be the purpose of the plenum, because there is no such thing in the ocean. This is true but it is also true that their are not millions of gallons of water in our aquariums. The use of an open water space or "plenum", under the sand bed accomplishes a number of things. Most importantly it keeps the sand bed at a low oxygen level (.1 ppm) rather than zero. This allows the sand bed to have little water movement and yet not have a problem with anaerobic spots which may release Hydrogen Sulfide, that rotten egg smell.
Sam Gamble has done a lot of research on the chemical aspects of the plenum, speaking with him at MACNA he reported finding pH readings as low as 6.5. The water in the plenum is also higher in organics and nitrates than the main water in the tank. This is because most of the detritus is pulled into the sand bed by the worms and other small animals. Any remaining nutrients in the main water are used by the corals and calcareous algae or may be removed by protein skimming. The plenum acts as a reservoir for the food sources of the denitrifying bacteria which inhabit the lower layers of the sand bed. These bacteria use the oxygen in nitrate (NO3) with organic carbon in their metabolism. Thus we are able to kill the proverbial two birds with one stone and achieve reduction of nitrate and organic levels.
I currently am running a number of tanks with this method of filtration and by far the most successful are the ones with grunge and janitors. My favorite is a 25 gal tank which has been set up since October 1995. As an experiment I have done very little to this tank as way of maintenance. It has 4-20 watt fluorescent bulbs two actinic and two daylights. The wholesale fish dealer I use has been gracious enough to give me small pieces of coral which have broken off large colonies and some which were about half alive. The results have been amazing! I have been able to get a wide variety of soft corals to attach and grow including Leather, Colt, Young, Xenia, Zoanthids, and a few others which I have not identified. I have also had a number of stony corals recover regrow their zooxanthelle, and flourish. These include Bullseye (Caulstrea), a Porities which was almost completely bleached, and a beautiful purple cup coral (Tubinaria) which was in really bad shape has done very well. Only a "crescent moon" portion around the edge survived but this has regained its health and is spreading back over the center portions. My favorite is a green open brain which had been thrown in the live rock tank because it was dying it was shaped like an hour glass. One half was rotten and very smelly I cleaned it by shaking it vigorously in saltwater and placed it in the tank. The half which wasn't rotten has recovered fully and is doing great. Some of the soft corals including the colt have gotten to big for this small crowded tank. They were being stung by the Porities, and have been moved into another tank. Their is no protein skimmer on this tank. One or two small water changes have been done.
The only additives are Reef Plus and Reef Complete both manufactured by Sea Chem. The only filtration is the sand bed with an Eco-Sand plenum system and two powerheads, one on a timer to alter currents. This tank has been purposely neglected. I have put different small fish in and saw no noticeable changes. The current occupants are a pair of Red Saddle Back clowns. This has to be the best aquarium I have ever had. I don't even clean the glass.
I am not advocating neglecting our aquariums. All Living things we keep in captivity need some maintenance. Even pet rocks need to be dusted. The point I am trying to make is that by using "live sand" filtration our tanks are very close to the balance found in nature. A few other "filters" will allow even better results. Many of the corals we keep use chemical warfare in their on going battle for space on the reef. This is one reason why it can be difficult to house large stony and soft corals in close proximity to each other. Protein skimming removes many of these chemicals, however these need not be huge pieces of equipment. Many of the smaller hang on the tank models work very well. Both activated carbon and absorption medias can enhance the performance of our reef. But there is no longer any need to spend hundreds or thousands of dollars on filtration equipment, rather use your money to duplicate the lighting conditions found on the reef.
The maintaining of our miniature ecosystems depends largely on the individual tank and the specimens kept. A tank full of soft corals has different requirements than one containing sps corals. In the soft coral tank emphasis would be more on iodine and nutrients, whereas in the sps tank it would be on intense lighting and calcium/carbonate levels. The soft coral tank would need little if any calcium replenishment whereas a heavily stocked sps tank may require more calcium/carbonate than the healthy mature sand bed could provide. In this situation a calcium/carbonate/strontium additive would be helpful for the long term health of your mini reef ecosystem.
Most tanks kept by hobbist today are a mixture of animals from all over the globe. It can be difficult to provide for the needs of all the varieties of animals in our tanks, but the Jaubert method gives us a very good tool. However before our sand bed can take care of our reef we must take care of it. Most sand beds will require a two to four month break in period when the parameters are stable but perhaps not at the exact levels we expect. Rashly pouring in additives because a month old sand bed is not pumping out tons of calcium will not help the long term stability of the aquarium, and may actually hurt it. One way to keep the animals happy and ensure a more stable environment is Regular Partial Water Changes. The best maintenance is patience and observation. Let the tank mature before purchasing delicate or hard to keep animals and know what they need before you purchase.
So is "live sand" the magic cure for all of our aquariums challenges. No not completely but it will provide a stable foundation on which to build our reefs and help us to give our marine animals and plants an environment closer to that which is in nature. It makes it easier to keep our "pets" for a very long time. Many of the animals we keep can live for decades. So being able to keep them alive for a few months or years really is not success. As we learn more about the complexities of the marine environment we gain an appreciation of the fragility of the world we live in. It is now possible to have and entire reef ecosystem all of which has been propagated in captivity. It is our responsibility to purchase wisely and to support businesses which help us to reach a balance between conserving and learning about our fragile world.