The Sandless Nano Reef Aquarium

How to create a sandless nano reef tank.

(Blastomussa merleti). Via IRD - Benzoni, F./Wikipedia

When the aquarium bug bit me, I decided to set up a somewhat small reef system in my office. I wanted this tank to be quite different from what could be called an average reef aquarium. To accomplish this, I went with a sandless system and used a foam product to decorate many of the tank’s inside surfaces. I also stayed with corals that would not quickly outgrow the nano tank and would do well with its lighting and water movement capabilities.

After much research, I decided to order a 34-gallon plug-and-play system, as I liked its completeness; it had a rear-located vertical sump containing two return-flow water pumps, a protein skimmer, a heater and a fitting for connecting a chiller or canister filter. And with its hood containing four LED moonlights, two 55-watt T5 power compacts and a built-in light controller, it seemed to fit my needs nicely.

When the aquarium arrived, I saved the white foam pad the aquarium was sitting on in its shipping box. I painted the foam pad’s edge the same silver color as the aquarium trim and then set the aquarium on top of it on a custom-built stand. The foam pad is an ideal substance (and insurance factor) to eliminate any unequal pressures a glass tank may develop if placed on a slightly uneven surface or one that may warp with age. After a leak check, I installed the equipment and then used a product called Handi-Foam (see my article “Foam Aquascaping” from the April 2011 issue of Aquarium Fish International magazine) to coat its inside back wall, most of the side panels and its bottom, as this aquarium would not contain a sandbed. I cemented egg crate pieces to the side panels to keep the foam from lifting off because it’s quite buoyant. I was going to add foam to the overflow, but I ran out of foam. The overflow can easily be removed and foamed later so that it looks like the other interior surfaces.

The foam creates a black lavalike environment almost identical to some found in Hawaiian waters. Since my office experiences wide temperature changes, the foam helps provide a more insulated enclosure and a more stable water temperature. Furthermore, different frag species can easily be attached to the foamed areas, making the interior look even more realistic. As for the foamed bottom, it’s different to say the least, but in my opinion it’s better-looking than an undecorated glass bottom. Since the outside view of the side foamed panels were not pretty, I decided to coat their outside surfaces with a silver water-based paint.

One of the reasons this aquarium was chosen was its “accessory” bracket for the hookup of a chiller or canister filter. The bracket, having two bayoneted five-eighths-inch hose barb connectors, snaps into a cutout on the upper rear aquarium frame back wall. In my setup, a canister filter and chiller were hooked up in a continuous loop with aquarium water. First, gravity flowed water to the chiller via one barbed fitting, then it fed directly from the chiller’s outflow port to the inlet side of the canister filter, where its pump returns water to the aquarium through the second barbed fitting. Therefore, no dedicated chiller pump was needed. I also added a wavemaker to one of the pump outlets, as a constantly changing direction of water flow will benefit all of the corals in the aquarium.

The No-Sandbed Controversy

As for the no-sandbed aspect of this nano tank, I had been discussing such an endeavor with friends and business associates, and it became quite clear there were some strong positions, especially from those noting the importance of a sandbed. Those discussions convinced me this aspect of the new system was necessary to try, even though some controversy might result.

We often go about replicating past practices without thinking about some of the details surrounding them. Hobbyists seem to take it for granted that their new aquarium must have a sandbed. They want to have a bed of substrate that provides various biological processes and also a natural-looking lagoonlike bottom in their aquarium. That’s quite understandable, but I’ve had reef aquariums that functioned quite efficiently without sandbeds. In fact, in the long-run, bare-bottom, low-tech reef systems seemed to have water quality that was at least equal to some of the more high-tech systems with sandbeds.

My first sandless system dates back to the late 1980s. It was a glass 320-gallon reef system (called an invertebrate system at that time), and people from all walks of life and businesses would come to our home to view it. Often, after visitors sat quietly for many minutes in front of the aquarium, appearing to be mesmerized by its environment, the first question they asked was “Why no sand on the bottom?”
I would then begin by explaining that there are major water quality differences between what occurs in the wild and in captive systems. In the ocean, the exchanges of water due to tidal effects are extremely large in reef areas, but those in captive systems are just the opposite. Wastes generated by life living within natural reef areas are either used by other life forms or swept away by currents into ocean depths.
Where there is not sufficient natural water exchange, such as in bays and inlets, pollution occurs to one level or another, and those can become fertile areas for unwanted forms of plants or algae and some organisms. Since major water exchanges such as those occurring in the wild are not feasible in closed systems, other ways to limit pollution in closed systems should be explored. And this system was an experiment to see if enough good bacteria existed on its other surfaces to keep the system healthy.

That always raised eyebrows and resulted in head nods — some in a positive fashion, others somewhat negative, depending on their level of experience. I would then go on to explain in general terms what occurs in the sandbed and that it was an accumulation area for animal wastes. And even though those wastes were partly used as foodstuffs for various bacteria and some infauna, most waste just accumulated. And if the sandbed was not vacuumed monthly, the sand simply got filthy. Some areas were impossible to clean because of rocks sitting on the sandbed, and these areas continued to accumulate detritus and detracted from being able to keep a clean and efficient sandbed.

That always got a positive response. I would then add, “If I could only keep a small percentage of the sandbed operating efficiently, why have it in the first place if it would work against me in trying to maintain an overall efficient system?” Keep in mind at that time there were no calcium reactors or phosphate or nitrate reactors. The only high-tech pieces of equipment were homemade trickle filters and 6500K metal halides. So at least in my opinion, a means to keeping this system free of accumulating detritus was a must-try!

After I got the point across about accumulating detritus within sandbed areas that were not cleanable, I shifted to how I go about collecting detritus on the bare bottom. As explained, in areas that could be reached by a siphon tube, it was sucked out, and the removed water was replaced with newly made seawater. As for detritus that collected in impossible-to-reach areas, a water pump was used to stir it up and into the aquarium currents. Some of this fed some of the corals in the aquarium, and some of the remaining detritus was carried to the system’s mechanical filters that were in the system’s three overflows (each rear corner and center area) and were cleaned right after. I also noted how easy it was to siphon out unwanted bristleworms.

The “no-sandbed” reasoning became quite plausible to my ongoing guests, and since this was an experiment, it was well-accepted by almost all who heard its reasoning. Most of what was described to these guests occurred in the system’s six- to 48-month time frame, and the system did extremely well, with various frags of somewhat rare corals for those days being sent to various companies and well-known individuals.
Unfortunately, the unexpected happened. As many hobbyists, I had a life event that made me need to quit aquariumkeeping for a time. We lost a child in a car accident with a second in a coma for six months. I had no time for my aquarium, so I gave the system to a local shop. But the no-sandbed experience stayed with me, and in future years I tried the method several more times — yet on smaller systems, as was my intention with this new nano tank.

Nitrogen Cycle Sans Sandbed

In today’s world, almost all hobbyists, especially those new to the hobby, think a sandbed is necessary for biological and scenery purposes. As for biological purposes, it’s not necessary here to discuss the technical aspects of the nitrification process. It should suffice to say that the sand is colonized by different classes of bacterium that reduce the toxicity of animal wastes and uneaten foods (ammonia-laden products are converted to less harmful substances such as nitrite and nitrate). Yet hobbyists with sandbeds almost always also use live rock in various amounts to decorate the aquarium. These living rocks do the same thing as the sandbed (i.e., provide a substrate inhabited by nitrifying bacteria). To what degree depends on the live rock’s porosity, but they are often initially used to provide the same bacteria so some animal life can safely and quickly be added to the new system.

Is that bacteria solely living on and in live rock sufficient to maintain a system? Before I answer that, realize that some of these bacteria exist on any coral, and they flourish on the inside aquarium panels (there is also more surface area in “foamed” systems) and any other aquarium surface. Therefore, would a system with no sandbed and some live rock that’s crowded and overfed have sufficient bacteria to process all wastes? Of course, it varies, as exceptionally overcrowded and overfed systems can have levels that become dangerously high. But in well-managed sandless systems with a reasonable amount of live rock, water quality will remain excellent, and the lack of a sandbed will not impact animal health. Where to draw the line when it comes to bioload in sandless systems is simply a matter of common sense.

Sandless systems also have fewer problems with unwanted algae growth, as their caretakers are always monitoring visible detritus accumulations and removing excesses, which is not possible in crowded and overfed systems with sandbeds and a lot of live rock. As for my latest venture into sandless systems, once the system was filled and its equipment up and running, I added live rock and allowed it to settle for a week. I used “branching” rock and elevated the majority of coral pieces off the bottom of the aquarium, thereby opening the bottom and back area to cleaning when needed.

In closing, I’ve helped one hobbyist in Australia and another in Hong Kong set up large sandless systems, and after six to 12 months, both are doing quite well, with coralline algae beginning to cover the bottoms of their tanks. And as for my new nano, it’s working perfectly and is so quiet that it would even make a perfect tank for the bedroom. 

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Article Categories:
Fish · Reef Tanks