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While I echo what others have pointed out (the low flow tanks were actually pretty decent flow, a wide open tank with frags has no dead spots or blocked flow, etc), huge thanks for BRS for having the guts to actually test these assumptions out.
tl;dr looks like I'm criticizing the heck out of what you're doing, I think you guys are doing great, just I think the setup/analysis may be a tad flawed. So my first thought when you mentioned your set up was "How was 66x turnover considered 'low'", then when you halved it even at 33x turn over you're calling this low. I think if anything you might be achieving a "flow saturation" so simply saying "double the flow" really doesn't tell the whole tale, it needs to be the right flow. That said comparing I think you need to understand your data a bit more, in the first case you have ~19% versus ~25% which doesn't look like much however tank 3 actually had 30% more weight growth than tank 1 did, and in the second case between tank 1 and 3 and the ~12% versus ~20% change, tank 3 had a 66% more growth than tank 1, and that in itself says something. If you guys every need help with numbers and analysis I'm more than happy to do it. That said, if I were to set up this experiment I'd try to go more apples to apples, which means only 2 pumps in all the tanks, that way the direction of the flow and the way it moves around the tank will be closer related so you can remove that as a factor and you can simply change the intensity of the pumps to determine difference in flow amount. Looks like tanks 1/2 the off set of pumps might actually create a gyre effect which where as tank 3/4 the pumps look to be clashing into each other creating a more turbulent/chaotic flow. Overall though keep doing what you 're doing, all the other stores are simply trying to sell you stuff by showing how cool it is, you guys are actually trying to show what works and what doesn't and I totally love you for it.
Honestly, I think both tests had the low flow rate too high. Do 10X turnover. I'd also like to see the test duration extended a bit more. 2 months is borderline.
@Brstv have you considered increasing the light in these tanks? In my experience with higher turnover rates the benefits don’t kick in unless you increase the photosynthesis. Love what you guys do keep up the amazing work.
Pretty much exactly what I expected. I only run about 30x flow in my tank and think that's over kill. Nutrient levels required for growth as well as light, temp and pH are critical for faster growth but I honestly believe the purpose of water flow is to create a homogeneous water column and that can be achieved with 20-30×. Great vid! As a scientist I really appreciate your experiments!
Well, that's surprising. I wonder how this would correlate to full grown colonies obstructing flow to each other? I would assume the higher flow would be more necessary/beneficial in that circumstance.
When you did the side to side comparison, I noticed that the corals in the tanks with higher flow grew shorter but branchier than the ones in the low flow tanks which seemed taller but less branchy. The short, branchier corals look more natural, so maybe high flow has it's benefits regarding coral appearance.
Awesome video and experiment! I am surprised by this. Just goes to show, spending exorbitant amounts for ridiculous amounts of flow is not necessary. Thanks you guys for doing this and yet again contributing to this wonderful hobby!
Could you guys do a video discussing bubble scrubbing in a reef tank? I would love to here brs’ take on the subject. Keep up the great work! Brs rocks!
Great test! Results are not that surprising - corals adjust to different conditions. In low flow they will have thinner, but longer branches, while in high flow they will look shorter but sturdier. It's observable in natural reefs.
The numbers seem a bit weird to me, or maybe I heard them wrong. Just using rough numbers from tanks 1 and 2... If one tank saw a 25% weight gain, while the second saw a 20% weight gain, then the first gained 25% more weight, not 5% more. Put another way. Tank one moves from 100 to 125 grams for a gain of 25 grams. Tank two moves from 100 to 120 grams for a gain of 20 grams. 25 grams is 1.25 times (or 25% more than) 20 grams...
Christopher Loggins my theory is that they are saying it was a 5% more not 25% relative to the other coral. Using you’re example 25g is 5% more from the base number than 20g is. I also agree with you that the vocabulary used here and on some of there other videos is somewhat incorrect. So you are correct there.
Was PH tracked at all during this round of testing? I’d be curious to know if more/less flow combined with a PH between 8.2 and 8.4 had any impact on the data. Interesting that based upon everything we’ve read and heard from the Pro’s and scientific community would contradict these findings.
Your test tanks are pristine and at the most controlled environment, I would be interested to find out if higher flow would have more of a “forgiveness” impact to a tank with less top of the line equipment and controlled environments to simulate everyday life. Basically allowing an average or even poorly maintained tank to still allow corals to thrive and fight off issues that may be there with low flow.
Maybe adding flow has diminishing returns from a certain point onward and 30times tank turn over is already enough. Also the benefits might not come in terms of growth but maybe the corals are more resilient or the skeletal structure is different, who knows. But the results were surprising, I totally expected high flow to lead to much faster growth.
I like the idea! Although when we do tests we try to only have one independent variable. This helps to ensure we do not confuse the data results based on another factor. (:
I'd be curious to see if exponential growth would affect results. I.e. do larger colonies exhibit faster rates of growth, and benefit more from extra flow? Good video, love the continued research, and we all benefit in the end with more insight you guys provide.
Not that surprising to me. I have a lps tank that only gets about 15x turnover, and it had much better growth than my sps tank that had close to 100x turnover So now everyone can stop buying $1000 worth of powerheads and get back to enjoying their tanks.
I think the results would differ more if these tanks where wider 48" plus, what is got from this is it doesn't hurt to increase flow. The thing is tank one probably had 5x more flow than a low flow common setup with underpowered or miss angled flow pumps combined with too much rock
I would have thought it would have been the dissolved oxygen/gas exchange that affects coral health and growth. Maybe an experiment with the same flow rates, but one with higher surface agitation could be a worthwhile experiment. aka pointing power heads at the bottom vs the surface
How old are these tanks? How established are these tanks? How much were the corals being fed? Aminos? What were the NO3/PO4 levels during that time? The list goes on. Too many variables.
The only two differences I would have done to the test is I would have ran them a lot longer as growth differences between frags are minoot. Second I would have used to separate display tanks running on the same just so that there is no water chemistry different. Then strictly go by weight
Speaking of mp10's I just added a build video and forgot to mention that the mp10 doesnt work on glass thicker than 3/8"..... crazy I see so many videos on youtube of people with rimless tanks with thick glass running mp10s.... how is this possible? Or are all of their tanks just 3/8 thick glass or less?!?!
I would be curious how your powerhead placement affected this.The powerheads aren't generating any direct flow on the corals because of how high they are. I wonder if you would have had more discrepant results if the power heads were lower and thus more directly affecting the corals themselves.
I noticed you dosed different ratios of Calcium & Alkalinity each day per tank. I was told to always add equal amounts of two part additives. Has this changed?
That is still the basic advice for beginners but reefers should really be testing alk and Ca and then adjust dosing as needed to maintain preferred levels.
Correct me if I'm wrong, but I thought with two part dosing you are always supposed to dose in equal parts? For example I measure alkalinity and if I need to add 20 ml of alkalinity I will 20 ml of Calcium as well. Have I been told incorrectly?
The quick answer: the recipe most reefers use for mixing Calcium Chloride is roughly equal to the max saturation/concentration that Soda Ash can be mixed to (which typically results in an equal dose of Alk/Ca). Sodium Bicarb has a lower max saturation/concentration than Soda Ash, roughly about half as much, which is why you are seeing nearly double the amount of Alk dosed per day versus Calcium. We use Sodium Bicarb in experiments like these to reduce the variable of increased pH, which can be a byproduct of Soda Ash.
From my gut feeling I would say that your data variability is too high and therefore you cannot make a statistically robust conclusion. You should sit down with a biostatistician to talk numbers ;) also, you might want to do a sub analysis of the different kind of corals and check if you can see a difference there. Your main challenge is that you probably do not have enough n to really get to reliable statistics. For this setup, I would also consider putting them all in one water circle to prevent any variability of other factors and consider a cross over set up (each coral would be its own control).
Very solid theory and my thoughts as well. We very much wanted to continue this test using a real-world tank environment with similar tank parameters and conditions, but it just turns out that these types of tests chew through time and resources and we just are not able to justify the huge effort of nearly year-long tests. There's so much more to learn here. Maybe one day we will be able to circle back.
@@BRStv Great work though fellas. You're right. There's so much to learn about reefing. I'm new to this but I'm learning from all y'all pros. Love the informative videos and gorgeous tanks. Y'alls work shows for itself...👊👍😎
This test is flawed. You can't add the best powerheads on the market to such small tanks, and talk low flow with +60 times turnover... Of course the influence on growth stagnates. The test should be done with cheap powerheads with 10-20x turnover, up to the best with 100 times turnover, and control group with cheap powerheads up to 100x and best with 10x. Then you'll see that flow pattern, laminar vs chaotic etc matters. The test really is a test to show cheap setups versus expensive setups. Having two MP10's right next to the corals like that will give ample flow no matter the settings.
You make a good point! If you watch our live stream we do talk about the changes we could make to these flow tests. We plan on putting more work into our flow experiments to get more reliable results. (:
More from BRStv Investigates!
➡ Best way to cure Live Rock : brs.li/BRStvInvestigates_LiveRock_Cure
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➡ ALL of our BRStv Investigates : brs.li/BRStv_Investigates_Playlist
Bulk Reef Supply can I buy one or two of those used DOS pumps at a discount?
I didn't realise that 66x turnover was considered low flow. I thought 40X was good for SPS.
While I echo what others have pointed out (the low flow tanks were actually pretty decent flow, a wide open tank with frags has no dead spots or blocked flow, etc), huge thanks for BRS for having the guts to actually test these assumptions out.
Yeah I definitely think the low flow tanks started way to high compared to most reefer with one junk sun sun power head in the corner 🤷🏻♂️
tl;dr looks like I'm criticizing the heck out of what you're doing, I think you guys are doing great, just I think the setup/analysis may be a tad flawed.
So my first thought when you mentioned your set up was "How was 66x turnover considered 'low'", then when you halved it even at 33x turn over you're calling this low. I think if anything you might be achieving a "flow saturation" so simply saying "double the flow" really doesn't tell the whole tale, it needs to be the right flow. That said comparing I think you need to understand your data a bit more, in the first case you have ~19% versus ~25% which doesn't look like much however tank 3 actually had 30% more weight growth than tank 1 did, and in the second case between tank 1 and 3 and the ~12% versus ~20% change, tank 3 had a 66% more growth than tank 1, and that in itself says something. If you guys every need help with numbers and analysis I'm more than happy to do it.
That said, if I were to set up this experiment I'd try to go more apples to apples, which means only 2 pumps in all the tanks, that way the direction of the flow and the way it moves around the tank will be closer related so you can remove that as a factor and you can simply change the intensity of the pumps to determine difference in flow amount. Looks like tanks 1/2 the off set of pumps might actually create a gyre effect which where as tank 3/4 the pumps look to be clashing into each other creating a more turbulent/chaotic flow.
Overall though keep doing what you 're doing, all the other stores are simply trying to sell you stuff by showing how cool it is, you guys are actually trying to show what works and what doesn't and I totally love you for it.
I would say it is obvious, too little flow is bad for growth but and more than good strong flow has limits. Correct?
Great info!
With little frags I wouldn’t expect much difference but with full grown colonies there will be a huge difference
Honestly, I think both tests had the low flow rate too high. Do 10X turnover. I'd also like to see the test duration extended a bit more. 2 months is borderline.
Another great addition to the reefkeeping knowledgebase
What you share with the community is invaluable.
Thank you very much !!
Wow! Results are really surprising. Thought for sure there would be a huge difference.
@Brstv have you considered increasing the light in these tanks? In my experience with higher turnover rates the benefits don’t kick in unless you increase the photosynthesis. Love what you guys do keep up the amazing work.
Pretty much exactly what I expected. I only run about 30x flow in my tank and think that's over kill.
Nutrient levels required for growth as well as light, temp and pH are critical for faster growth but I honestly believe the purpose of water flow is to create a homogeneous water column and that can be achieved with 20-30×.
Great vid! As a scientist I really appreciate your experiments!
Well, that's surprising. I wonder how this would correlate to full grown colonies obstructing flow to each other? I would assume the higher flow would be more necessary/beneficial in that circumstance.
Jarrod Hall this was what went through my mind too.. Frags with open space around them would require much less flow than large multibranch colonies.
When you did the side to side comparison, I noticed that the corals in the tanks with higher flow grew shorter but branchier than the ones in the low flow tanks which seemed taller but less branchy. The short, branchier corals look more natural, so maybe high flow has it's benefits regarding coral appearance.
Another well done vid!
Cool project. I wondered about detritus removal from fish
Awesome video and experiment! I am surprised by this. Just goes to show, spending exorbitant amounts for ridiculous amounts of flow is not necessary. Thanks you guys for doing this and yet again contributing to this wonderful hobby!
Could you guys do a video discussing bubble scrubbing in a reef tank? I would love to here brs’ take on the subject. Keep up the great work! Brs rocks!
Great video many thanks 😀👍🏴
Great test! Results are not that surprising - corals adjust to different conditions. In low flow they will have thinner, but longer branches, while in high flow they will look shorter but sturdier. It's observable in natural reefs.
The numbers seem a bit weird to me, or maybe I heard them wrong. Just using rough numbers from tanks 1 and 2... If one tank saw a 25% weight gain, while the second saw a 20% weight gain, then the first gained 25% more weight, not 5% more. Put another way. Tank one moves from 100 to 125 grams for a gain of 25 grams. Tank two moves from 100 to 120 grams for a gain of 20 grams. 25 grams is 1.25 times (or 25% more than) 20 grams...
Christopher Loggins my theory is that they are saying it was a 5% more not 25% relative to the other coral. Using you’re example 25g is 5% more from the base number than 20g is. I also agree with you that the vocabulary used here and on some of there other videos is somewhat incorrect. So you are correct there.
Surprising results! Thanks for taking on this experiment, saved me from buying a couple of extra powerheads!
Very interesting test. Thank you for doing this.
Was PH tracked at all during this round of testing? I’d be curious to know if more/less flow combined with a PH between 8.2 and 8.4 had any impact on the data. Interesting that based upon everything we’ve read and heard from the Pro’s and scientific community would contradict these findings.
Your test tanks are pristine and at the most controlled environment, I would be interested to find out if higher flow would have more of a “forgiveness” impact to a tank with less top of the line equipment and controlled environments to simulate everyday life. Basically allowing an average or even poorly maintained tank to still allow corals to thrive and fight off issues that may be there with low flow.
Maybe adding flow has diminishing returns from a certain point onward and 30times tank turn over is already enough. Also the benefits might not come in terms of growth but maybe the corals are more resilient or the skeletal structure is different, who knows. But the results were surprising, I totally expected high flow to lead to much faster growth.
You should of did 1 with high light vs low light along with low flow low light vs high flow high light
I like the idea! Although when we do tests we try to only have one independent variable. This helps to ensure we do not confuse the data results based on another factor. (:
Did Tim “the toolman” Taylor visit the BRS warehouse??? More Power 💥
I'd be curious to see if exponential growth would affect results. I.e. do larger colonies exhibit faster rates of growth, and benefit more from extra flow? Good video, love the continued research, and we all benefit in the end with more insight you guys provide.
Not that surprising to me. I have a lps tank that only gets about 15x turnover, and it had much better growth than my sps tank that had close to 100x turnover
So now everyone can stop buying $1000 worth of powerheads and get back to enjoying their tanks.
Do you run any stat tests to see if there is any significant differences?
I think the results would differ more if these tanks where wider 48" plus, what is got from this is it doesn't hurt to increase flow. The thing is tank one probably had 5x more flow than a low flow common setup with underpowered or miss angled flow pumps combined with too much rock
What are those orange fish in the tanks?
What’s the species of orange fish that you guys had in these tank? I’ve never seen them before! Thanks BRS!
They're lemon damsels 🙂
Very interesting results
nice job and corals
I would have thought it would have been the dissolved oxygen/gas exchange that affects coral health and growth. Maybe an experiment with the same flow rates, but one with higher surface agitation could be a worthwhile experiment. aka pointing power heads at the bottom vs the surface
How old are these tanks? How established are these tanks? How much were the corals being fed? Aminos? What were the NO3/PO4 levels during that time? The list goes on. Too many variables.
Yes
The only two differences I would have done to the test is I would have ran them a lot longer as growth differences between frags are minoot. Second I would have used to separate display tanks running on the same just so that there is no water chemistry different. Then strictly go by weight
Put tank 5 with T5 fixture... +400% coral growth...
Can save money!
The experiment is kind of messed up because 66x is extremely high already...
Tank 3 was dirtier than tank 1 on the egg crates\
66 times turnover isn't low flow
What were the fish that you had in these tanks?
Coral do not grow that fast on egg crate.
What are the fish in the tanks?
Speaking of mp10's I just added a build video and forgot to mention that the mp10 doesnt work on glass thicker than 3/8"..... crazy I see so many videos on youtube of people with rimless tanks with thick glass running mp10s.... how is this possible? Or are all of their tanks just 3/8 thick glass or less?!?!
Likely at, or close to this without the spacer. If thicker you likely have to move to an MP40 though.
I would be curious how your powerhead placement affected this.The powerheads aren't generating any direct flow on the corals because of how high they are. I wonder if you would have had more discrepant results if the power heads were lower and thus more directly affecting the corals themselves.
Certainly a variable that could be tested! 🙂
I noticed you dosed different ratios of Calcium & Alkalinity each day per tank. I was told to always add equal amounts of two part additives. Has this changed?
That is still the basic advice for beginners but reefers should really be testing alk and Ca and then adjust dosing as needed to maintain preferred levels.
Double the cost! Double the sales! Double the amount of life support!
Even though high flow doesn’t make our corals grow faster. Should we still have high flow for the health of the corals and the reef?
Yes but it depends on the coral they all like a certain amount of current or i should say they do better in what they lime
Did you notice less detritus buildup with more powerheads?
I had a buddy turn his mp40 up all the way and his coral grew really well
Was this on auto sync or both mp40 on reefcrest
Correct me if I'm wrong, but I thought with two part dosing you are always supposed to dose in equal parts? For example I measure alkalinity and if I need to add 20 ml of alkalinity I will 20 ml of Calcium as well. Have I been told incorrectly?
Are your corals absorbing both at the same rate?
The quick answer: the recipe most reefers use for mixing Calcium Chloride is roughly equal to the max saturation/concentration that Soda Ash can be mixed to (which typically results in an equal dose of Alk/Ca). Sodium Bicarb has a lower max saturation/concentration than Soda Ash, roughly about half as much, which is why you are seeing nearly double the amount of Alk dosed per day versus Calcium. We use Sodium Bicarb in experiments like these to reduce the variable of increased pH, which can be a byproduct of Soda Ash.
Bulk Reef Supply thanks very much that makes sense since I’m using soda ash and not sodium bicarbonate
That’s true with some additives but not all. I dose 125ml a day of alk and only 18ml of calcium solution
High flow for me 😂
Excellent research. what corals where used?
Shocking results..now all we know about flow for years gone to trash ?
From my gut feeling I would say that your data variability is too high and therefore you cannot make a statistically robust conclusion. You should sit down with a biostatistician to talk numbers ;) also, you might want to do a sub analysis of the different kind of corals and check if you can see a difference there. Your main challenge is that you probably do not have enough n to really get to reliable statistics. For this setup, I would also consider putting them all in one water circle to prevent any variability of other factors and consider a cross over set up (each coral would be its own control).
Anyone else wish he said: "Dos DOS Dosers"?
😂
Your test was flawed. It's not the low flow or high flow that matters, it's the circulation of flow and eliminating deadspots. Just my theory...👊👍😎
Very solid theory and my thoughts as well. We very much wanted to continue this test using a real-world tank environment with similar tank parameters and conditions, but it just turns out that these types of tests chew through time and resources and we just are not able to justify the huge effort of nearly year-long tests. There's so much more to learn here. Maybe one day we will be able to circle back.
@@BRStv Great work though fellas. You're right. There's so much to learn about reefing. I'm new to this but I'm learning from all y'all pros. Love the informative videos and gorgeous tanks. Y'alls work shows for itself...👊👍😎
This test is flawed. You can't add the best powerheads on the market to such small tanks, and talk low flow with +60 times turnover... Of course the influence on growth stagnates. The test should be done with cheap powerheads with 10-20x turnover, up to the best with 100 times turnover, and control group with cheap powerheads up to 100x and best with 10x. Then you'll see that flow pattern, laminar vs chaotic etc matters. The test really is a test to show cheap setups versus expensive setups. Having two MP10's right next to the corals like that will give ample flow no matter the settings.
man this is insane... this is comparing high flow to "insane" flow. Not "Low flow" to "High Flow." This is somewhat dishonest...
You make a good point! If you watch our live stream we do talk about the changes we could make to these flow tests. We plan on putting more work into our flow experiments to get more reliable results. (:
First comment :)