Kenbow19 said:
The way you suggest measurement would require linear flow, the flow in my tank is very turbulent and would not do well in your test, so does that mean my flow is not OPTIMAL. I would suggest members research their corals needs and use the best location available in the tank based on the General flow requirments listed in Bornemans book and others.
Certain water flow meters (even expensive ones) would not accurately work in some reef applications. For the food test (which is a crude way of measuring flow) the direction of the flow is not important. Are you telling me you experience a net velocity of 0 cm/s around your coral? I understand a reef tank (as far as the immediate area surrounding the coral) is almost always turbulent, even when provided with laminar flow. However, there is almost always a net force in a particular direction. A particle will probably change in velocity and possibly direction. The direction of the particle will produce less than a straight line in some instances (hence a loss in accuracy). If your currents reverse direction and the particle travels in reverse this is o.k. We won't use "negative" distances. It is not important in our measurements which way the flow is going at a particular time. We will need to take say 10 or so measurements. In this way we can obtain a high, low, and average velocity for each desired area. This method will be a bit easier and more accurate when used in conjunction with a video camera. I understand it is neither very sophisticated nor terribly accurate. We are not trying to produce statistically significant results that would hold up when defending a doctoral thesis. This test does provide a simple way to obtain a ballpark estimate of water velocity in a meaningful unit.
There have also been other proposed, relatively simple, mechanisms to obtain meaningful measurements in comparison to the natural coral reef such as the clod card technique. This method would define flow as the loss of mass /dissolution rate/diffusion factor, so it would not be in a velocity unit, but still comparable to the natural coral reef (and the available field data) and to other reef tanks.
http://www.int-res.com/articles/meps/93/m093p175.pdf
How do you propose somebody meets the needs of the corals if they have nothing to define high, medium, low flow or measure their own? Should we just define medium flow as a flow between low and high? Than we can define low flow as lower than medium and high, and high flow as higher than medium and low
. Or we could logically come up with a way to measure water flow in understandable, comparable units. In this way we could make comparisons between other aquariums and the natural environment.
