Why do corals need flow

[Flatlandreefer]

Everybody knows that the key to a successful reef tank is proper flow throughout the tank. Why do corals need proper flow to thrive/survive, why will corals die in stagnant or moderate flow conditions?

 

[dpulve]

From my understanding to deliever Oxygen and nutrients. Flow and surface agitation also helps with the release of gases. Sure there are a ton more reasons but the big mystery is how much flow???

 

[Sk8r]

They have no hands. They can't reach after, move to get, or chase food. They eat light, but they also take in and exude liquid.

 

[Dkuhlmann]

That's a loaded question. Dpulve hit on the main reasons and others include to keep them clean of algae and to facilitate spawning. Leathers need lots of flow to help them with their shedding process they go through to remove algae and whatever other irritants they have and they grow after each shedding session.

I bet if you did a Google for why do corals need flow and place Julian Sprung in the request you would find much more on the subject.

 

[Jscwerve]

From my understanding to deliever Oxygen and nutrients. Flow and surface agitation also helps with the release of gases. Sure there are a ton more reasons but the big mystery is how much flow???

From all that I've read so far, the correct answer to that question is "more".

 

[ZKicka4000]

Current also flushes away waste and debris. Without nutrients and oxygen constantly being brought to the coral an CO2 and debris being flushed away, photosynthesis and respiration would be hindered. Imagine being locked in an air tight closet for a while...... it wont be long now.

 

[Flatlandreefer]

So without flow a coral would die of the "coral equivalency of suffocation" not necessarily starvation first?

 

[ZKicka4000]

Not sure which it would die from first, all of the above would likely be a contributing factor.

 

[billdogg]

From my understanding to deliever Oxygen and nutrients. Flow and surface agitation also helps with the release of gases. Sure there are a ton more reasons but the big mystery is how much flow???

From all that I've read so far, the correct answer to that question is "more".

LOL

Especially for stony corals, it is difficult to provide too much flow, for all of the reasons listed above. As an example, my 120g DT has ~ 700gph provided from the return pump, and another 7700gph or so from power heads, so a total of ~ 8400 gph total flow or 70x turnover per hour. I'm considering adding a little more.

 

[CStrickland]

You do want to be careful with some softer corals though. Things like euphylia and bubble corals that are like a skeleton of plates that the flesh pokes out between. Those ridges of bone can be fairly sharp, so if the soft flesh gets whipped around it can get cut on its own bones. These coral like a flow that sort of fluffs them from under neath, bringing food and shaking off waste and things that might settle on it. Hard directional flow, and sudden blasts will tear them, or keep them hiding for safety (if they stay receded they can't grab food from the water or light.)

So, like a lot of reef questions, the answer is "it depends"