Undergravel Filter

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Natural substrate materials of coral reef origin assist greatly in maintaining a proper chemical balance and can be used to create authentic and unusual aquarium microhabitats.

2. On top of the eggcrate, one or more layers of plastic window screening are used to prevent the sand from falling through to the plenum, the area underneath the grid where wa-

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ter, but no sand, is present. This is important, as the plenum must remain unobstructed and contain only water. (Before adding any live substrate, the system should be filled with saltwater and circulation systems activated.)

3. Enough sand to create a layer 1 to 2 inches deep is placed on the screen. This should be silica sand, crushed coral, or other material that will not

Crushed Coral

Chapter Three 95

Plenum Deep Sand Bed

homemade jaubert-style plenum perfect-a-flow undergravel filter reef renovators' eco-sand filter plate pen plax undergravel filter

Simple grids that can be used in Monaco-type systems, in which a layer of hypoxic water is formed under layers of sand. Homemade versions are easily constructed using plastic eggcrate and fiberglass screening, with off-the-shelf options also available.

readily dissolve. Aragonite should not be used for this layer, or it may eventually turn into a chunk of "concrete." This is the denitrification layer and should remain undisturbed. Aragonite can be used in the upper layer, where the activities of burrowing organisms will prevent solidification.

4. A second layer of screening is placed atop the first sand bed. On top of this, another 1 to 2 inches of substrate is placed. This looks and works best if composed of aragonite, live sand from the ocean, crushed coral, and crushed shell fragments, with about half the total amount being aragonite and/or live sand. This material will slowly dissolve and be replaced by small amounts of new aragonite as the system matures. The live sand portion is to provide a seeding of beneficial organisms (see below for how to determine the weight of materials needed).

5. There should be vigorous water movement created by pumps, powerheads, airstones, or some combination thereof. Lighting can be minimal or none at this stage. Dr. Jaubert's original systems do not employ protein skimming, but have very low loading of dissolved organics, primarily, in my view, because of their small fish populations. If the aquarium does have a large bioload, protein skimming can and should be used to minimize the water's organic content. Early discussions (Frakes, 1993a, 1994) of the Jaubert method suggested, incorrectly, that protein skimming would be detrimental, as it might deprive beneficial organisms of a needed energy source. Dr. Jaubert has publicly corrected this misinterpretation of his work, however

6. Enough ammonium chloride solution is added to give

3.0 ppm on a good ammonia test kit. Commercial preparations are available, or use a 6% (w/v) solution of reagent

96 Natural Reef Aquariums grade NH4C1 in distilled water. This is added along with the live sand.

7. Nitrite is measured with a test kit, beginning about a week after the ammonium chloride is added and continuing every few days. You will see a peak of nitrite, followed by a decline to zero. At this point, about 30 days after the live sand/ammonium chloride was first added, you will have enough nitrate in the water to be detected by a test kit. The pH will have fallen during this time. It can be maintained by adding limewater during the whole process, enough to compensate for all evaporated water, or by using a commercial pH buffer. Sodium bicarbonate (household baking soda) can also be used as a buffer additive. A solution containing about 1 teaspoon (5 gm) of soda in 1 pint (500 ml) distilled water can be added to the tank for each 10 gallons of water and the resulting effect on pH noted. It is then possible to determine how much of the solution to add to move the pH to the desired reading. Changing the pH of the aquarium by additions of chemical should always be done slowly, so that a few tenths of a pH unit of change occurs over several days time. Maintaining the pH during this phase of the aquarium's development is not crucial but will make life easier later on.

8. Nitrate is now measured every few days. As anaerobic bacteria grow in the lower sand layer, the nitrate is converted to nitrogen gas, which escapes into the atmosphere. When the nitrate level is down to zero, perhaps 3 to 4 weeks later, the bacterial populations of the tank are established and stable.

At this point, live rock is added to create the reef structure, the lights are turned on, and the system is developed like a Berlin-style reef tank. If maintenance of pH, alkalinity, and calcium were not done during the cycling period, they are adjusted now, and a regular routine of maintenance is established. The tank will undergo a series of algae blooms for the next six to eight weeks, during which time only mo bile organisms, and especially those that help with "housekeeping" such as Astraea snails, brittle stars, hermit crabs, fish, etc., are added. When the algae blooms stop and the tank starts growing coralline algae, photosynthetic invertebrates can be added. As long as the water chemistry is maintained, the system will grow and develop from this point with little effort (apart from maintenance duties, of course) on your part.

Additional Considerations in tlie Monaco-Style Aquarium

1. Adding the live rock along with the live sand will speed the nitrogen cycle along considerably. Some people prefer to add the live rock periodically in small amounts, because of the cost. This is also acceptable.

2. To figure out how much substrate you need, calculate the volume of the sand bed in cubic inches, using the following equivalents:

1 pound of live sand = 14 cubic inches

1 pound of aragonite, live rock fragments, or shell fragments = 23 cubic inches.

Example: Let s say we want a 2-inch layer of sand in the bottom of a 75-gallon tank that has a base of 4' x IV2.

48" x 18" x 2" = 1,728 cubic inches.

If you use all live sand, you will need

1,728 14 = 123 pounds of sand.

For a half-and-half mix, about 40 pounds of rock fragments and 60 pounds of sand will be required.

3. To construct the reef itself, you will need about 1 pound of cured Pacific Islands live rock for each 1 gallon of water capacity, if the aquarium is constructed in a standard, rectangular tank. This much live rock makes a stack about three-quarters the height of the tank and running the full length of the tank, allowing plenty of room for water flow.

4. While Dr. Jaubert relies on the dissolution of the

Chapter Three 97

aragonite alone to replenish both calcium and carbonate ions in his systems, you will probably find that a densely populated home system needs either additions of limewa-ter or more aragonite and additional maintenance. I would rather add the limewater than do other maintenance. The end result will be the same in either case.

5. Add substrate sifting animals as soon as tests indicate that the development of bacterial activity in the sand bed is complete. This would be at the same time that live rock and algae-eating organisms are added. The idea is to establish the community of "utilitarian" species that will help to maintain the environment for the Pivotal Species to occupy the aquarium later.

The Simplified Live Sand Approach

The notion of having a plenum with a layer of "dead" water at the bottom of the aquarium strikes some hobbyists as either unnatural or too complicated. A number of Americans have modified the Jaubert method simply by adding a layer of live sand several inches deep to reef aquariums already containing significant amounts of live rock. Virtually all believe that the sand provides valuable denitrification and helps provide calcium and buffering capacity to their systems.

Speaking at the Western Marine Conference in San Francisco in 1996, hobbyist Larry Jackson advocated building one's live rock structure directly on the bottom of the aquarium and then filling with aragonitic sand (live or dried) to a depth of two to three inches. Jackson uses only one layer of sand, but keeps it physically active with the presence of small sea cucumbers and other burrowing organisms. His own recipe for creating live sand is to mix oolitic aragonite with coarser "Samoa Pink" reef sand and let this bed become colonized with beneficial bacteria, worms, and other organisms through contact with healthy live rock.

"I like to keep things simple, and I've had good luck without going to the trouble of building a plenum," Jackson said. "Why bother?"

In exchanges on Internet aquarists' forums (see Selected Sources, page 307), others have reported similar success without the use of a plenum, but some hobbyists have also experienced the development of pockets of hydrogen sulfide gas in live sand beds that do not have the benefit of a plenum. Jaubert and others suggest that the plenum allows a very slow diffusion of water and gas through the sand, thus avoiding noticeable hydrogen sulfide problems.

Some hobbyists have found that placing the bulk of their live sand over a plenum in the sump, rather than in the display tank, makes for easier maintenance and fewer problems with fishes disrupting the deeper sand. For those with established reef tanks, a remote sump allows one to add the advantage of live sand without tearing down the aquarium. Such a sump, devoid of predatory fishes, can also become a haven for delicate organisms and a settling basin for larvae of various species.

Until controlled experiments are done, these various creative methods of employing live sand will remain within the realm of home aquarists developing their own tech-

Jaubert Method

The live sand system in action: note the gas bubbles, blue-legged hermit crab, and sand-sifting goby, all part of the working environment

98 Natural Reef Aquariums

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  • steven
    How deep crushed coral for undergravel filter?
    8 years ago
  • douglas
    Do undergravel filters work with sand?
    7 years ago
  • gail pond
    Can you use undergravel filter with sand bed?
    7 years ago
  • Terttu
    Do ubdergravel filter work with sand ?
    7 years ago
  • Linda
    How to make a Jaubert Plenum Style NNR Filter?
    6 years ago
  • macario
    How to make layers of undergravel aquarium?
    5 years ago
  • chiaffredo
    How to build a jaubert plenum?
    5 years ago
  • Marmadoc
    Can you use crushed coral with an undergravel system?
    5 years ago
  • fabrizia
    How to make a homemade undergravel filter?
    5 years ago
  • pervinca
    How an undergravel filter works?
    5 years ago
  • jonne
    Can you do a reef with an under gravel filter?
    3 years ago
  • Elle
    What depth of sand bed for a undergravle filter in a reef tank?
    3 years ago
  • Ermenegilda Padovesi
    Can live aragonite sand be placed over a undergravel filter in a saltwater aquarium?
    4 months ago

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