RBDG Frequently Asked Questions
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Why are Reef Balls better than other artificial reefs?
Reef Balls are superior to many other materials for the following reasons:
1) An artificial reef should not contain toxins that leach into the sea water.
Tires are known to leach petroleum compounds and other nastiness.
Some older military ships contain large amounts of PCBs.
Many "Materials Of Opportunity" (i.e. cars, barges, etc.) contain toxins.
2) An artificial reef should not contain biologically active compounds like copper, iron, zinc, chromium, or fertilizers.
Steel objects favor the growth of marine plants and invertebrate that need iron. Although this stimulates the growth of some species, it does not stimulate a natural growth and the species diversity and densities will not mimic natural reefs.
3) An artificial reef should remain stable on the bottom and last for hundreds of years.
Many objects are just too light or have too high of a profile compared to their weight to remain stable on the bottom. These objects will move around in storms tearing up the natural reefs as they move. In the process of moving, the growth is often lost. Even when the growth remains, it is oriented differently to sunlight and currents and may die.
If the objects don't last long enough (i.e. steel rusts) the corals that settle on the structure just fall off. Many corals don't get to adequate spawning sizes until they are over a hundred years old. So if the goal is to help coral ecology, short lived materials are not suitable.
4) Reef Balls Are Designed For The Life They Support
Reef Balls have holes that not only go into the module but between the walls. The large open area in the center is designed to provide fish shelter. The holes are designed to create vortexes which feed the invertebrates and corals. Many other artificial reefs assume that surface area or profile alone will support fish. Profile only attracts (but does not support) certain types of fish. Raw surface area without the right composition is just dead space (surface area needs current, light or both to be productive).
5) And a real reason Reef Balls are best is cost.
The cost to hire a barge and crane for a single day is generally at least $10,000. Without the option for a floating deployment style, even "materials of opportunity" are too costly. When all costs are considered, Reef Balls are the most economical designed artificial reefs the in world.
How Should I Deploy My Reef Balls
Many people want to know if the Reef Balls should be spread out or piled high. Deployment patterns have a major effect on the type of life that will use your reef. Only the goals of your project can best answer the question. In absence of goals, just arrange your Reef Balls in a pattern similar to your observations of the natural reefs in the area. Dr. Bill Lindberg is studying deployment patterns now and can probably assist if your goals include the recruitment of specific fish species. Generally however, fishing reefs are better spread out and diving reefs need to be tightly deployed. A combination of the two makes an excellent reef.
Why is pH Neutralized Concrete Important (What's Microsilica For)?
Regular concrete has a high pH when it is first cast. This is caused by excess calcium hydroxide in the concrete. Over time in water (or even rain) the calcium hydroxide slowly leaches out. Eventually, the pH of the concrete in the sea will approach the pH of the sea which is about 8.3. However, this leaching (which takes about 3-6 months in sea water) is toxic to many types of marine life. Some types, like barnacles, are resistant to the pH difference so the growth that occurs on concrete that is not pH neutralized will favor those species. By the time the pH is normal, the resistant species have settled and set up defenses to repel settlement of other marine life forms to the reef. We recommend that if microsilica is not available that you let your concrete cure in the rain or a freshwater pond for about 3-6 months before deployment. If microsilica is available, the correct dose will bring the pH to about 8.3 right away. (Microsilica reacts with calcium hydroxide to form a type of cement "glue" that actually makes the Reef Balls stronger).
How Do We Insure Stability?
Many clients ask us how to anchor their Reef Balls. First, it should be understood that Reef Balls were designed so that they would NOT require anchors unless in shallow high energy areas. In most cases, the weight distribution and hydrodynamics of the modules will keep them in place through even the worst storms. However, any object in the ocean can move under extreme conditions and the direct hit of a major hurricane is nearly impossible for any object to withstand. If you feel that your reef needs anchoring, we have developed several techniques to make it easy. To make attachment points, just use a 1/2 inch stainless steel I-bolt with a large washer attached to the end, and place it between the side flanges about 6 inches above the bottom of the mold. You may need to drill a hole right at the flange joints for large bolts. Leave the circle in the I-bolt sticking out of the flange. You can add as many of these attachment points as you need for anchors.
Now, you just need to select an anchor and attach it to the I-bolt. We suggest the use of stainless steel airplane cabling to connect the anchor to the I-bolt. House trailer tie down anchors are inexpensive, but may only last 10-20 years. Double helix anchors are available that have a much greater holding strength, but they also cost more.
Another trick is to wrap a house trailer tie down anchor (just the bottom screw part) in a paper bag with sand in it. Coat the shaft with several layers of sugar water, letting each layer dry. Position the anchor in the mold just like the I-bolt at a 45 degree angle leaving a foot or more sticking out of the flange. After casting, flush the shaft with a garden hose to make sure it breaks free from the concrete. On the ocean floor, just tap the shaft into the sand. Then screw it in tight.
Did They Really Outlaw The Use of Cars In Alabama?
As of January 1, 1997, car bodies are not allowed on the large area permit in Alabama. Car bodies have never been legally allowed on Florida's LAP.
Can PVC Plastics Be Used As A Reef Material?
Yes, the Army Corp of Engineers still allows the use of PVC plastics in the construction of DESIGNED artificial reefs only. PVC, however, has a charge that attracts bacterial microbes which can cause an unnatural settlement of marine growth. PVC is also known to be light weight and brittle--often breaking down with age. The only artificial reefs currently using PVC are experimental or fitted with large concrete slabs for stability. Even with the concrete, PVC reefs have not yet been proven to be long lasting. Occasionally, Reef Ball allows the use of PVC air filled capsules encased fully in the top of our Reef Balls. The purpose of this is to provide a highly visible "signature" on depth finders to easily locate Reef Ball reefs. These capsules are not intended to be exposed to the open ocean.
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