The Importance of correct flow in the marine tank.

Discussion in 'Idol Marine' started by Idol Marine, 16 Jan 2015.

  1. Idol Marine

    Idol Marine

    17 Apr 2012
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    As we have developed a better understanding of the processes occurring in our reef tanks, equipment has been developed that mimics some of the natural conditions. Sadly, one major aspect which is one of the most noticeable aspects of the natural reef, water movement, is often overlooked. This is unfortunate in that creating adequate water movement can be one of the relatively least expensive aspects of setting up a reef tank, and one of the most important. Proper water movement goes a long way toward helping a reef system thrive.
    The importance of water movement
    Organisms present on the reef are accustomed to an environment with strong water movement. Anyone that has been out diving or exploring along a reef quickly realises how difficult it is to remain in one spot due to the force of the water around him or her. This rapid and constant water movement has caused life in the sea to develop physiologically to make use of the water moving around them. This is especially true of the sessile invertebrates, such as corals and clams that are a wonderful addition to any aquarium. These organisms have developed to make use of the currents bringing them such things as food, oxygen, and nutrients, as well as carrying away their waste products.
    Most corals have little capacity for removing waste material from their surface. This is especially true of the SPS corals, which owing to their relatively small amount of living tissue, do not waste their energy removing waste material, but rather depend on the water moving around their surface to clean them. When you look at the physiology of these corals closely, it can be seen that much of their body is designed for nutrient capture, while very little is designed for waste removal.
    In addition to providing essential nutrients, and instrumental in waste removal, water movement also influences:
    • Growth of corals
    • The formation of new coral colonies
    • Growth of problematic algae
    • Fish health
    Growth of corals

    Changes in Size
    Several authors have reported that new growth of Acropora is often spindly relative to the growth of the old colony, when this colony is placed in a position with less water movement (Veron, 1986, Sprung, 1994). However, if the flow is increased, the corals may resume their original growth pattern, and the speed of growth may also increase even if all other factors remain the same. This increased flow not only increases the thickness of the new growth, but the previously spindly growth may thicken as well. Author Dana Riddle has found that the growth rate of many stony corals could be increased dramatically by increasing the flow of water around them. Interestingly, his studies were contrary to the belief that lighting intensity determines growth, in that he found that strong water movement stimulated faster growth than increased light intensity.
    Changes in Growth Pattern
    Water movement may change the growth pattern of some corals. For example, Acropora palifera normally grows as thick, unbranched colonies on the portion of the reef where wave action is greatest (Veron, 1986). However, when placed in some reef tanks with less water movement, these corals begin to grow in a more branched manner similar to other Acropora species.
    The manner in which you have your water flow directed will also affect the way your corals will grow. All corals have polyps that need to be extended for feeding and if these are directly in the flow they will not extend and the coral will eventually die.
    Problematic algae
    Most algal blooms result from excess nutrients being present. In reef tanks, these patches of algae usually are in spots where there is little to no water movement. As a result, detritus settles in these spots. That is why, if algae are plucked from these spots, a cloud of detritus is usually raised as well. In order to reduce this "algal oasis," it is necessary to get more water movement over these areas. Therefore, one of the goals of good water movement is to keep the detritus in suspension long enough so that much of it can be removed by the filtration system, or so that it can settle in the sump, where there is little light, and can be removed later.
    In a study conducted at Eilat in the Red Sea, it was found that soft coral colonies located in areas where sedimentation did not occur due to strong water movement, grew three times faster than did colonies where sedimentation was a problem (National Geographic Explorer, TBS, May, 1993). This reaction to sedimentation has several applications in captive reef systems. If sedimentation is allowed to occur on stony corals, the result will be bleaching in those areas of the coral where the sediment remains. This bleached area often becomes a site where detritus settles and soon thereafter, problematic algae begin to grow. Therefore, strong water movement is essential not only for growth, but also to keep algae from becoming problematic. In soft corals, when detritus settles on them, spots develop under the detritus that rot or cause black spots on the colony which can eventually lead to the coral's demise.
    Fish health
    Another often-overlooked aspect of water movement is its effect on fish health. If you look at the labels of many fish foods, you will find that one of the largest components is fat. This is an important component in nature in that fat is quickly converted into energy. This is great for fish in the wild, as these fish are, for the most part, very active and require large amounts of energy. If, however, fish are placed in an environment where they do not have to fight the current, the result can be the development of fatty deposits, and as a consequence, a shortened lifespan.
    Water movement flow patterns
    There are three main types of water movement, each with very different characteristics:
    • Laminar flow: Laminar flow is straight, unidirectional flow, like that produced from a powerhead, or at the latter stages of a wave whose energy has been channelled in one direction by the reef.
    • Surge: Surge is similar, only on a larger scale. To an observer viewing a school of fish, surge is when the school remains in the same pocket of water, but due to surge, the pocket of water and the school of fish suddenly move six feet in one direction, and just as quickly move back.
    • Turbulence: Turbulence is the random flow of water in multiple directions. Of the three flow patterns, turbulence is the most desirable and the most difficult to produce (Sprung, 1998).
    There are many types flow pumps available for your display tank. One must always remember that your return pump from your sump must NEVER be considered a flow pump, your return is just that a return pump to ensure the water from your sump is returned to your tank.
    Please contact us for any advice on the most suitable solution for your tank, we have many flow pumps available depending on your requirement and needs.​
    Last edited: 16 Jan 2015
    tekkengal likes this.

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