Does high flow really matter?

[Pistondog]

How to Grow Corals Quicker, Part II: Combined Effects of Water Velocity and Alkalinity Concentrations

If we want to grow corals more quickly, it helps to understand the interplay of the many variables that affect corals. Dana explores the relationship between alkalinity, water flow, photosynthesis, and nutrients.

reefs.com

 

[Afterburner]

How to Grow Corals Quicker, Part II: Combined Effects of Water Velocity and Alkalinity Concentrations

If we want to grow corals more quickly, it helps to understand the interplay of the many variables that affect corals. Dana explores the relationship between alkalinity, water flow, photosynthesis, and nutrients.

reefs.com

Now we are getting closer to some real research on this. Thank you. One of my questions still is ”what is high flow?” Dana gives the value of 3.9 in/sec as high flow rate. I am just wondering what 3.9 in/sec looks like in a tank, since I don’t have a Flo-meter.

 

[fish farmer]

Now we are getting closer to some real research on this. Thank you. One of my questions still is ”what is high flow?” Dana gives the value of 3.9 in/sec as high flow rate. I am just wondering what 3.9 in/sec looks like in a tank, since I don’t have a Flo-meter.

Looks like you are going to have to buy a flow meter to validate that the flow in your tank is truly "low" vs "high".

Much like using a Par Meter to dial in your lights instead of the "looks good to my eyes".

 

[Pistondog]

Now we are getting closer to some real research on this. Thank you. One of my questions still is ”what is high flow?” Dana gives the value of 3.9 in/sec as high flow rate. I am just wondering what 3.9 in/sec looks like in a tank, since I don’t have a Flo-meter.

Left the flow on when feeding 1 time. Watched a food particle and did the 1 Mississippi thing. More than 3, less than 5 inches/sec, in the middle of a 20g. MP10 at 40%.

 

[MaxTremors]

Max, I’m not going to get in a ticking match with you, since you obviously can’t or won‘t back it up with an actual research paper, but if you read the article I sent you, they account flow with bringing in cooler water to the reefs, and nowhere does it say directly what you summarized as the previous quote. Here is the actual previous quote you reference directly before the quote I referenced
“High temperature is very stressful to corals,” Rogers said. “If there’s not enough exchange of water from the open ocean, those areas do not do well.”
Not surprisingly, in reef zones around the atoll that had less moving water, coral cover was much sparser, since there was little cool inflow to offset rising water temperatures.


I’m done discussing this with you unless you can provide some actual research links.

I don’t know what you want. Do you want research papers that show how water flows over natural reefs? Here you go:

https://journals.ametsoc.org/downloadpdf/journals/phoc/43/7/jpo-d-12-0164.1.pdf

Wave-Driven Circulation of a Coastal Reef–Lagoon System

Abstract The response of the circulation of a coral reef system in Kaneohe Bay, Hawaii, to incident wave forcing was investigated using field data collected during a 10-month experiment. Results from the study revealed that wave forcing was the dominant mechanism driving the circulation over...

journals.ametsoc.org

Do you want studies about how flow affects morphology? Here you go:

Effects of coral colony morphology on turbulent flow dynamics

Local flow dynamics play a central role in physiological processes like respiration and nutrient uptake in coral reefs. Despite the importance of corals as hosts to a quarter of all marine life, and the pervasive threats facing corals, characterizing the hydrodynamics between the branches of...

journals.plos.org

Here is a series of articles that goes fairly in-depth about why adequate flow is important (it’s not a peer-reviewed study, but it’s in-depth and you’d be hard pressed to find a better series that covers the topic as it relates to reef aquaria).

Water flow is more important for corals than light. Part 1. Introduction to Gas Exchange

Considerations for water flow are almost always secondary to other decisions made when assembling a reef set up when in fact, water flow is paramount to the health and vitality of a reef system.

reefs.com

Water flow is more important for corals than light. Part II: The science of corals and water flow

This second article in the series will review some of the published scientific research describing how water flow affects coral health.

reefs.com

Water Flow is More Important for Corals Than Light Part 4: Basics of Hydrodynamics

This article revisits the topic of hydrodynamics, at a larger scale, in order to give readers background understanding on the big picture of water movement.

reefs.com

Water Flow is More Important for Corals Than Light, Part V

Just as aquarium lighting has received a thorough reevaluation, so too must we start to consider how the water movement of our aquariums translates into water motion which is relevant and suitable for coral health.

reefs.com

Heres the deal though, you’re the one making an assertion. You’re the one claiming that decades of thought and experimentation on water flow as it relates to reef aquaria is wrong. So, the burden of proof is on you. As far as I’m concerned, and I’m sure most experts in the hobby agree, that adequate flow is very important, and that fact is as close to ‘settled science’ as anything can be in this hobby. We know, objectively, that corals receive orders of magnitude more ‘flow’ in the wild than they do in our tanks, that is indisputable.

So now it’s your turn to show us some evidence supporting your claim. Convince us to turn the pumps off.

 

[areefer01]

So now it’s your turn to show us some evidence supporting your claim. Convince us to turn the pumps off.

That isn't what they are suggesting or even implying. They are looking to discuss flow, aquarium needs, and the effect of various hobbyist biotypes. Seems pretty straight forward. They know flow is important. But how much? Where are the studies? Or is it just marketing hyperbole (look no further than the vibrant discussion).

They are at least open to reading suggested papers. Sheesh.

 

[Afterburner]

I don’t know what you want. Do you want research papers that show how water flows over natural reefs? Here you go:

https://journals.ametsoc.org/downloadpdf/journals/phoc/43/7/jpo-d-12-0164.1.pdf

Wave-Driven Circulation of a Coastal Reef–Lagoon System

Abstract The response of the circulation of a coral reef system in Kaneohe Bay, Hawaii, to incident wave forcing was investigated using field data collected during a 10-month experiment. Results from the study revealed that wave forcing was the dominant mechanism driving the circulation over...

journals.ametsoc.org

Do you want studies about how flow affects morphology? Here you go:

Effects of coral colony morphology on turbulent flow dynamics

Local flow dynamics play a central role in physiological processes like respiration and nutrient uptake in coral reefs. Despite the importance of corals as hosts to a quarter of all marine life, and the pervasive threats facing corals, characterizing the hydrodynamics between the branches of...

journals.plos.org

Here is a series of articles that goes fairly in-depth about why adequate flow is important (it’s not a peer-reviewed study, but it’s in-depth and you’d be hard pressed to find a better series that covers the topic as it relates to reef aquaria).

Water flow is more important for corals than light. Part 1. Introduction to Gas Exchange

Considerations for water flow are almost always secondary to other decisions made when assembling a reef set up when in fact, water flow is paramount to the health and vitality of a reef system.

reefs.com

Water flow is more important for corals than light. Part II: The science of corals and water flow

This second article in the series will review some of the published scientific research describing how water flow affects coral health.

reefs.com

Water Flow is More Important for Corals Than Light Part 4: Basics of Hydrodynamics

This article revisits the topic of hydrodynamics, at a larger scale, in order to give readers background understanding on the big picture of water movement.

reefs.com

Water Flow is More Important for Corals Than Light, Part V

Just as aquarium lighting has received a thorough reevaluation, so too must we start to consider how the water movement of our aquariums translates into water motion which is relevant and suitable for coral health.

reefs.com

Heres the deal though, you’re the one making an assertion. You’re the one claiming that decades of thought and experimentation on water flow as it relates to reef aquaria is wrong. So, the burden of proof is on you. As far as I’m concerned, and I’m sure most experts in the hobby agree, that adequate flow is very important, and that fact is as close to ‘settled science’ as anything can be in this hobby. We know, objectively, that corals receive orders of magnitude more ‘flow’ in the wild than they do in our tanks, that is indisputable.

So now it’s your turn to show us some evidence supporting your claim. Convince us to turn the pumps off.

From your sources
”It should be noted that even though the coral on the right was grown in higher water flow, it took about twice as long to grow to the same occupied volume but it had more than twice the mass of the lower flow specimen.”

Plus, I don’t ever remember saying anything about making my tank stagnate and not having any flow at all. I just think (not confirmed) that a lot of tanks I see have way too much turbulence.

 

[Afterburner]

Max, The last section of the information you provided really drives home the need for water flow, and it seems that turbulance is what they are trying to produce to get water flowing on all sides of the coral and inside the colony.

Conclusions​

The reef aquarium hobby has a long way to go before our understanding of water flow catches up with what we know about reef aquarium lighting. Like the “Watts per Gallon” moniker that came before it, the use of “turnover rate” to describe water movement continues to cripple the progress of more advanced water movement techniques. By encouraging the formation of one or more gyres, aquarists are capable of producing more water movement in terms of overall water flow speed. Since higher flow speeds produce greater amounts of turbulence, this translates into increased gas exchange and higher rates of photosynthesis and respiration.

But, it seems from other sources that corals grow well in moderate flow, just differently and at similar rates. My conclusion from this is that due to the lower amount of water flow inside a dense colony, it focuses it’s growth outward to provide a less dense colony of similar size. From what I have found, if the water quality is excellent, the coral will adapt and be healthy.’’

It seem like there needs to be a lot more research done on this topic before we can just tell everyone to go get an electric outboard motor and put it in one corner of your tank. This thread has convinced me to replace my gyre when I get home from skiing though, but I am removing the other smaller spot pumps and just going with laminar flow with occasional reversing direction. I will probably experiment at different levels of flow to get the best aesthetics and not worry about the actual amount of flow. Due to being a mixed reef, I can just look at the goni’s, torches and hammers to see that there is flow and adjust accordingly. This might not be what the “settled science” seems to define as correct, but I am not sure the this science is really settled anyway (read the bold comment from the study above).

 

[Raphael Dalmeida]

I've been in the great barrier reef a few times here in Australia, there are some times that the current is not that strong and great for sight seeing.

Although a many times the flow is super strong that really tires you out even with the fins. So you could say it's variable where it can go super strong.

On top of that there are usually multiple currents going through the reef, bringing nutrients, animals etc.

Id be keen to better understand turbulent flow though.