OK so here are some of the things I actually wrote down:
Respiration-compensation-saturation-Inhibition
A respiring coral needs a certain amount of light for zooxanthellae to compensate. Then with increasing light there is increased efficiency in respiration until the saturation point. This saturation point can be increased with increased flow/water exchange around the coral which reduces the oxygen around the coral and increases the efficiency of respiration. If light is increased above the saturation point you can reach the point of inhibition where the excessive light actually inhibits efficient respiration. Jake translated this to the hobby stating that more light needs more flow in order to be beneficial (and even potentially avoid deleterious effects from exceeding the inhibition point). Said if a coral has reached photo saturation then polyps on the top and/or in low flow may appear retracted while those in low light/high flow will look better on the same colony. The flow on a reef is around 20cm/sec and is not replicated in the average aquarium even though lighting is getting close to natural levels.
Viscosity-resistance-inertia
Viscosity is dominate on a small scale, inertia is dominate on a lg scale. slow flow will yield more laminar flow, high flow will yield more turbulent flow due to resistance. There are boundary layers near stationary objects (rock, coral, tank glass) where flow is minimal.
Jakes suggestions:
Aim flow over the top of the tank where there is less flow and parallel to the long side of the tank so there is less resistance. The water has to circulate back around to the pumps so the flow through the bottom of the tank will have to match.
Make directional flow- all water in an aquarium is turbulent anyway and hobbyists are getting hung up on that. Directional flow uninterrupted for 18-24 inches allows the build up of inertia and overall flow in the tank is increased.
Switch the flow periodically (ie several times a day/ every hour- not every few sec) using timers hooked to flow sources in opposite sides of the tank running only those on a single side at one time. Jake recommends a DJ light timer called the chauvet 4005 which sells for about $30 and can accommodate 4 sources.
Use penductors to increase flow- Sharkreef will now carry a threaded penductor for use with pressure rated pumps
Other stuff was talked about, but I did not write it down-sometimes I just listen and forget to write.
Hope that helps Ed.
Cheers,
Tracy
