Does high flow really matter?

[Afterburner]

I guess there has been a missunderstanding from my original post. I am not talking about the number of times your tank's water turns over for the high flow. What I was talking about is all the other little or big extra pumps inside the DT that just move the same water around inside the tank. I am not sure we need and incredible amount of flow across everything in every part of the tank. My corals both SPS and LPS seem to do fine, even the ones with very little current or flow across them. Maybe the don't grow at the maximum speed, but they seem healthy to me and look better with more polyp extension. I actually want less growth so I am not pruning and trying to figure out what to do with all the frags at this point in my tank's maturity. My DT is a corner tank, so to get the flow that many say is needed everywhere in the tank, I would have to have a bunch of pumps cluttering up that beauty of the reef. I understand if people like the look of unnatural pumps inside the tank, or the constant blowing of corals, but I just think that the comments about how this is a proven fact that many SPS need high flow is erroneous from my real world experience. After all, there are these vase tanks that have nothing more than an air stone slightly moving the water and the corals grow fine as long as they keep the salinity in check.

 

[MnFish1]

I guess there has been a missunderstanding from my original post. I am not talking about the number of times your tank's water turns over for the high flow. What I was talking about is all the other little or big extra pumps inside the DT that just move the same water around inside the tank. I am not sure we need and incredible amount of flow across everything in every part of the tank. My corals both SPS and LPS seem to do fine, even the ones with very little current or flow across them. Maybe the don't grow at the maximum speed, but they seem healthy to me and look better with more polyp extension. I actually want less growth so I am not pruning and trying to figure out what to do with all the frags at this point in my tank's maturity. My DT is a corner tank, so to get the flow that many say is needed everywhere in the tank, I would have to have a bunch of pumps cluttering up that beauty of the reef. I understand if people like the look of unnatural pumps inside the tank, or the constant blowing of corals, but I just think that the comments about how this is a proven fact that many SPS need high flow is erroneous from my real world experience. After all, there are these vase tanks that have nothing more than an air stone slightly moving the water and the corals grow fine as long as they keep the salinity in check.

My guess is that you have a ton of flow

 

[Afterburner]

My guess is that you have a ton of flow

Not really. My half of my gyre broke off a while ago, and that is all I have in my 90gal corner tank. The half that is still working basically has been pointed down for a while blowing on a couple of goni's and the rest of the tank barely moves because the return pump mainly moves the surface and is probably way undersize for the tank yet for some reason everything is healthy. Go figure. All I have in this weird shaped tank is a single gyre because it is sort of hidden near the top on one wall.... been there so long that some coral spawned and is growing on it. I think in the past three years, I cleaned it once when there was no flow at all coming out of it.
I have a replacement for the gyre that I will put in place when I get back from a vacation I am on all next week, I just don't want to change anything major like flow the day before I leave town. It's bad enough that my Bengaii will give birth next week in my Xenia fuge and probably get eaten since I won't be here to move them to a brooder.

 

[mindme]

I think the concept of flow in reef tanks is really flawed, but I have no idea how to make it better.

Is flow speed? When I think of people saying "high flow", I am thinking they mean that the water is moving at a high speed. That is after all what higher volume pumps do, they push the water out faster/harder.

But when I look at the speed the pumps put out, I doubt the ocean is generally moving that fast. They have more flow in terms of water volume, but not in terms of speed. But all I seem to get from pumps is more speed to get more volume. But I want the volume at lower speed.

Wavemaking kind of achieves this. You can get a lot of volume moving back and forth compared to the speed of the water. But all I've been able to achieve this way is really short pulses. I'd like to get some longer pulses, but I don't think that's really possible.

It may just be impossible to get more volume at lower speeds in our tanks. On the bright side, it still works.

 

[monkeyCmonkeyDo]

Why i chose waveboxes and the large diameter seawirls. Not seasweeps but seaswirls.
D

 

[Jubei2006]

Like some on there I think "high flow" meaning strength of the pump isnt that important. We know a jet of flow will strip tissue off coral. I think we need to think more in terms of "bulk flow". The ocean obviously is a huge mass of water. It isnt moving in a pinpoint jet (I guess the major currents would be that, but theyre still huge). The ocean however moves a ton of water in bulk flow. If I can use a smaller pump and get the entire body of water moving in a synchronous pattern (like a standing wave) or the surge devices, they would be just as if now more effective than blasting a jet of water at a high velocity. Too bad surge tanks are difficult to hide the reservoir, I'd probably set up the big tank that way.

 

[areefer01]

I hear a lot about needing less flow or current for some corals, but does it really matter much to have high flow. Seems like all the pump vendors show off these incredible flow tanks that look like the inside of a washing machine. I can tell you that I have SCUBA dived reefs all over the world, and never been in any high current situations. I know that having some flow is essential, but how much is really needed? I currently have a mixed reef tank for the past 5 years and I never had and incredible amount of flow in it. I forget to clean my gyre and it ends up hardly pumping at all, yet the corals seem to grow fine with good polyp extension, so does high flow really matter?

Does having afterburner matter on certain tactical airframes? Similar have you ever dove say in Cozumel (Drift Diving)?

Search on Eric Borneman and the need to breath (part 1 - 3). Good read. It does matter. The problem new and some existing hobbyist are running into is the social media and content web that doesn't understand these theories or have little knowledge on the subject outside anecdotal.

 

[JJHodges]

I hear a lot about needing less flow or current for some corals, but does it really matter much to have high flow. Seems like all the pump vendors show off these incredible flow tanks that look like the inside of a washing machine. I can tell you that I have SCUBA dived reefs all over the world, and never been in any high current situations. I know that having some flow is essential, but how much is really needed? I currently have a mixed reef tank for the past 5 years and I never had and incredible amount of flow in it. I forget to clean my gyre and it ends up hardly pumping at all, yet the corals seem to grow fine with good polyp extension, so does high flow really matter?

Sounds like you’ve already decided I. The answer to your own question…

 

[MnFish1]

IMHO - there are numerous reasons for higher flows in our tanks - oxygenation, being the main one. local toxin removal another. among several. I have seen the 'wave makers' that cause coral to move 1/4 inch in one direction - and then the other every couple seconds - just a personal preference - it gives me a headache - and I'm not sure its accomplishing oxygenation or anything else. except moving coral a little. Of course people swear by these - all good.

 

[Mbritt]

I like the stronger coral. The key is keeping it less direct and more of a surge. My dive experience over the last 20+ years has shown me most reefs have a certain level of surge back and forth whether its softies or sps. These zones of course vary based on tides and storm. I think a good mix of current cycles is key. As you can see my softies are pretty happy with a good level of current. My video is too big, had to put it on Youtube.

 

[Afterburner]

Does having afterburner matter on certain tactical airframes? Similar have you ever dove say in Cozumel (Drift Diving)?

Search on Eric Borneman and the need to breath (part 1 - 3). Good read. It does matter. The problem new and some existing hobbyist are running into is the social media and content web that doesn't understand these theories or have little knowledge on the subject outside anecdotal.

To answer your first question, I have done a beach dive in Cozumel, but not a drift dive. I do not do many charter dives, but I have done charter drift dives at the Great Barrier Reef and in the Dry Tortugas. Most of my dives are from my own yacht now as I have an air compressor on board and mainly in the Keys and Bahamas.

I did look at the articles you mentioned, and his conclusion seems to be the opposite of your comments. Here is one of the conclusions from the article.
”

• Powerheads and recirculating pumps do not appear to greatly increase the oxygen saturation state of seawater aquaria. Instead, they probably serve to move oxygenated waters to areas of the tank that are locally lower in oxygen resulting from respiration within the tank.

This extensive reserch seems to agree with my observations in my tank that moderate water flow works fine. From the research, it seems like having a skimmer and a reverse cycle algae scrubber are the most effective at keeping hypoxia at bay. I currently run both of these along with a home made CO2 scrubber. It was interesting to read the relating article referenced about cardinal fish mouth brooding and sensitivity to oxygen levels since i have a mating pair of Bengaii the recently spit up 35+ babies and already has another mouth full.

 

[Afterburner]

Does having afterburner matter on certain tactical airframes? Similar have you ever dove say in Cozumel (Drift Diving)?

Search on Eric Borneman and the need to breath (part 1 - 3). Good read. It does matter. The problem new and some existing hobbyist are running into is the social media and content web that doesn't understand these theories or have little knowledge on the subject outside anecdotal.

I want to thank areefer01 for directing me to actual research on this subject, and thought it would be a good idea to reprint the conclustions here to save others from reading the entire 3 part research series.

Conclusions and Recommendations While this work is not comprehensive, it does indicate that some methods are better than others at maintaining or increasing oxygen levels. Based on what I have shown in this paper, the following conclusions and recommendations are made: Reef tanks approximate the cyclical nature of oxygen dynamics found in the field. Variation on daily and seasonal cycles is the rule rather than the exception on natural coral reefs, and appears to be the rule in reef aquaria, as well. Aquaria can and do become hypoxic at night and such a state may pose a risk to hypoxia-intolerant organisms. Cloudy water in shipping containers and tanks is a cause for concern as oxygen levels are measured to decline rapidly and to very low levels. Gas impermeable bags packed with an oxygen cap result in high water oxygen levels even over long periods of time. The levels are, in some cases, extremely high and may be a cause for concern in hyperoxia-sensitive species. Gas permeable bags are not permeable enough to ensure adequate oxygen levels in bags containing living specimens over normal overnight shipping durations. Aquaria can and do become saturated or supersaturated with oxygen during the day, and this is a result of oxygen resulting from irradiance of photosynthetic organisms. In no case was saturation or supersaturation measured without photosynthesis. Airstones and skimmers appear to be a very effective means of oxygenating small water volumes. Their effect on larger water volumes appears to be less. While the effect may be relative, the larger tanks and systems described here utilized powerful skimming or air pumps, and to gain an equivalent amount of oxygen as occurs in small water volumes would likely require air pumps or skimmers far larger than those commonly employed by aquarists. This includes data from a coral farm where very large commercial sized skimmers and high surface area/volume ratios failed to produce water even nearly saturated with oxygen at night with a heavy coral population. Powerheads and recirculating pumps do not appear to greatly increase the oxygen saturation state of seawater aquaria. Instead, they probably serve to move oxygenated waters to areas of the tank that are locally lower in oxygen resulting from respiration within the tank. Using algae in reverse daylight tanks appears to be an effective means of keeping oxygen levels at normoxic levels at night. This effect is pronounced even in tanks and systems that employ protein skimmers and airstones.

 

[Afterburner]

Overall, this just seems like a really bizarre thing to be questioning, as it is, for all intents and purposes, settled science. As I said above, corals are highly adaptable, and so long as they’re getting enough flow to respirate and photosynthesize, they’ll survive, but to truly thrive, they need a good amount of flow (again, what constitutes a ‘good amount’ varies depending on species).

Max, where did you get the information to state that this is “settled science’? Maybe you could provide a link to a research paper.
I investigated a little more, and most of the research I have found relates to to fluid dynamics in the ocean with respect to reefs health is related to the fluid dynamics effects on temperature. I did find this one comment that seems to also agree with my assumptions.
”The researchers also found that coral health suffered when there was high wave stress around the outer edges of reefs – heavy pounding that inflicts physical damage. High wave stress may become more common as climate change proceeds and sea levels rise. Conversely, protected reefs subject to less intense pounding had higher levels of healthy coral cover.”
This was from “

How do wave dynamics and water flows affect coral reefs?​

Understanding what aids or degrades these sensitive ecosystems can help focus conservation efforts on the reefs most likely to survive climate change.
September 16, 2016
|
Elizabeth Svoboda
”

 

[MaxTremors]

Max, where did you get the information to state that this is “settled science’? Maybe you could provide a link to a research paper.
I investigated a little more, and most of the research I have found relates to to fluid dynamics in the ocean with respect to reefs health is related to the fluid dynamics effects on temperature. I did find this one comment that seems to also agree with my assumptions.
”The researchers also found that coral health suffered when there was high wave stress around the outer edges of reefs – heavy pounding that inflicts physical damage. High wave stress may become more common as climate change proceeds and sea levels rise. Conversely, protected reefs subject to less intense pounding had higher levels of healthy coral cover.”
This was from “

How do wave dynamics and water flows affect coral reefs?​

Understanding what aids or degrades these sensitive ecosystems can help focus conservation efforts on the reefs most likely to survive climate change.
September 16, 2016
|
Elizabeth Svoboda
”

It’s settled science in that it’s what the hobby has collectively learned over decades of reef keeping, informed by what we know about coral biology/physiology, the amount of flow on natural reefs, and the effects of inadequate or inappropriate flow in reef tanks. It’s also common sense. In my original comment I went over the specific reasons why adequate flow is important, I think using terms like ‘high’ and ‘low’ sort of misses the point.

Also, in the article that you posted a quote from, in the paragraph directly before the part you quoted, it says that corals in areas with higher flow had better growth rates, weird how you left that out.

How do wave dynamics and water flows affect coral reefs?

Understanding what aids or degrades these sensitive ecosystems can help focus conservation efforts on the reefs most likely to survive climate change.

engineering.stanford.edu

 

[Shooter6]

I personally think there's a bit of misconception on the amount of flow in anyone's reef vs the ones in the ocean.

First point is the Florida reefs are much different then those in the redsea,Australia, Bali ect. As far as corals.
Secondly if you were able to swim in front of your wavemakers, and compare that to the flow in the ocean you would find the wavemakers don't compare at all to the amount of water movement on the reefs. An easy way to see the real movement on a reef is to take a bottle of ab+ and squirt it out.
Even on the relatively calm Florida and Caribbean reefs you will see it move back and forth about 10 ft, before quickly dissipating to nothing.

While our wavemakers make high streams of flow, the actual movement is no where near reefs.

If you get down into the channels between rocks and corals the flow is increased as it channels around these structures as well.

 

[areefer01]

To answer your first question, I have done a beach dive in Cozumel, but not a drift dive. I do not do many charter dives, but I have done charter drift dives at the Great Barrier Reef and in the Dry Tortugas. Most of my dives are from my own yacht now as I have an air compressor on board and mainly in the Keys and Bahamas.

I did look at the articles you mentioned, and his conclusion seems to be the opposite of your comments. Here is one of the conclusions from the article.
”

• Powerheads and recirculating pumps do not appear to greatly increase the oxygen saturation state of seawater aquaria. Instead, they probably serve to move oxygenated waters to areas of the tank that are locally lower in oxygen resulting from respiration within the tank.

This extensive reserch seems to agree with my observations in my tank that moderate water flow works fine. From the research, it seems like having a skimmer and a reverse cycle algae scrubber are the most effective at keeping hypoxia at bay. I currently run both of these along with a home made CO2 scrubber. It was interesting to read the relating article referenced about cardinal fish mouth brooding and sensitivity to oxygen levels since i have a mating pair of Bengaii the recently spit up 35+ babies and already has another mouth full.

You did more than most would. You actually read his work and that is all I would ask and come to your own conclusion. Dealing with similar flow challenges a lot of "my" mistakes are around the aquascape and dead spots as the a few of my corals matured. Thus why I referenced his work. That and he is just good at it - check out the reef beef episode he was on.

With regards to drift dives in Cozumel. If you are ever in the area you should try a couple. Diving through the reef wall passages, bottom, changing depths, and the current speed is pretty interesting. As you move over the reef you get to see all the interaction of fish with the various reef structures be it crest, wall, or rubble.

Sound like you have a good deal going - keep it up! Oh - and apologies if I came in too hot!

 

[areefer01]

I want to thank areefer01 for directing me to actual research on this subject, and thought it would be a good idea to reprint the conclustions here to save others from reading the entire 3 part research series.

​

Conclusions and Recommendations While this work is not comprehensive, it does indicate that some methods are better than others at maintaining or increasing oxygen levels. Based on what I have shown in this paper, the following conclusions and recommendations are made: Reef tanks approximate the cyclical nature of oxygen dynamics found in the field. Variation on daily and seasonal cycles is the rule rather than the exception on natural coral reefs, and appears to be the rule in reef aquaria, as well. Aquaria can and do become hypoxic at night and such a state may pose a risk to hypoxia-intolerant organisms. Cloudy water in shipping containers and tanks is a cause for concern as oxygen levels are measured to decline rapidly and to very low levels. Gas impermeable bags packed with an oxygen cap result in high water oxygen levels even over long periods of time. The levels are, in some cases, extremely high and may be a cause for concern in hyperoxia-sensitive species. Gas permeable bags are not permeable enough to ensure adequate oxygen levels in bags containing living specimens over normal overnight shipping durations. Aquaria can and do become saturated or supersaturated with oxygen during the day, and this is a result of oxygen resulting from irradiance of photosynthetic organisms. In no case was saturation or supersaturation measured without photosynthesis. Airstones and skimmers appear to be a very effective means of oxygenating small water volumes. Their effect on larger water volumes appears to be less. While the effect may be relative, the larger tanks and systems described here utilized powerful skimming or air pumps, and to gain an equivalent amount of oxygen as occurs in small water volumes would likely require air pumps or skimmers far larger than those commonly employed by aquarists. This includes data from a coral farm where very large commercial sized skimmers and high surface area/volume ratios failed to produce water even nearly saturated with oxygen at night with a heavy coral population. Powerheads and recirculating pumps do not appear to greatly increase the oxygen saturation state of seawater aquaria. Instead, they probably serve to move oxygenated waters to areas of the tank that are locally lower in oxygen resulting from respiration within the tank. Using algae in reverse daylight tanks appears to be an effective means of keeping oxygen levels at normoxic levels at night. This effect is pronounced even in tanks and systems that employ protein skimmers and airstones.

Don't thank me - I came in too hot and actually owe you an apology. As I noted above you did more than most would. Not only question me but read up on the subject by a respected fellow in the industry. So thank you honestly.

 

[Afterburner]

It’s settled science in that it’s what the hobby has collectively learned over decades of reef keeping, informed by what we know about coral biology/physiology, the amount of flow on natural reefs, and the effects of inadequate or inappropriate flow in reef tanks. It’s also common sense. In my original comment I went over the specific reasons why adequate flow is important, I think using terms like ‘high’ and ‘low’ sort of misses the point.

Also, in the article that you posted a quote from, in the paragraph directly before the part you quoted, it says that corals in areas with higher flow had better growth rates, weird how you left that out.

How do wave dynamics and water flows affect coral reefs?

Understanding what aids or degrades these sensitive ecosystems can help focus conservation efforts on the reefs most likely to survive climate change.

engineering.stanford.edu

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.

 

[Afterburner]

You did more than most would. You actually read his work and that is all I would ask and come to your own conclusion. Dealing with similar flow challenges a lot of "my" mistakes are around the aquascape and dead spots as the a few of my corals matured. Thus why I referenced his work. That and he is just good at it - check out the reef beef episode he was on.

With regards to drift dives in Cozumel. If you are ever in the area you should try a couple. Diving through the reef wall passages, bottom, changing depths, and the current speed is pretty interesting. As you move over the reef you get to see all the interaction of fish with the various reef structures be it crest, wall, or rubble.

Sound like you have a good deal going - keep it up! Oh - and apologies if I came in too hot!

Thanks for the advice on a Cozumel drift dive. I rarely go on organized dives like drift dives because I almost always dive with either a collection net or a speargun. Most of the guided trips do not let you bring either. If you are ever in Florida and have time for a dive, just let me know.

 

[areefer01]

Thanks for the advice on a Cozumel drift dive. I rarely go on organized dives like drift dives because I almost always dive with either a collection net or a speargun. Most of the guided trips do not let you bring either. If you are ever in Florida and have time for a dive, just let me know.

Thank you kindly and also for the conversation. If we should ever meet I think it would be fun. All the best.