# Is too much flow bad?



## Jaap (3 Aug 2014)

Hi

I was wondering if too much flow will cause plants not to grow...of course the plants dont get uprooted....so is too much flow bad for plants?

Also is too much co2 bad for plants?

Thanks


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## Tim Harrison (3 Aug 2014)

Sure, there will come a point where they will start to suffer mechanical damage, and will expend more energy repairing it than actually increasing biomass and growing. But I guess it's not just flow that's a factor, it's also turbulence...some macrophytes thrive in very fast flowing streams. But then again macrophytes strongly modify water flow, which in turn provides an environment conducive to growth.


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## Victor (3 Aug 2014)

Jaap said:


> Also is too much co2 bad for plants?


 No, too much CO2 will never damage your plants. They just will become less efficient at uptake CO2 in a tank that has too much of it.


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## Jaap (2 Oct 2014)

How does someone know he has too much flow? By adding fish to the tank and observing them maybe? Because eleocharis parvula isnt growing and some people in the forum suggesyed too much flow...


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## parotet (2 Oct 2014)

IMO too much co2 will damage your fish, not your plants. Maybe I'm wrong but plants will not care if there is an excess of gas in the water column.
Regarding the flow I think most of our tanks have a much slower flow that most of the aquatic habitats. The problems comes of course when plants are uprooted or when the soil is disturbed (because the soil won't be washed away down the river)... If you do not have these problems my guess is that your flow is ok. Now that I'm trying to achieve a high plant density in a high tech plant, my only way is high flow... Otherwise I get stagnant areas with poor nutrient and co2, thus problems. Different setups will have different flow patterns and velocity. Once again some fish can be affected, especially those living in stagnant waters. Just observe their behaviour.

My problems with Eleocharis were solved with frequent and hard trimming, good co2, medium light, frequent siphoning and patience...

Jordi


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## foxfish (2 Oct 2014)

There was chap about a year ago or so, on this forum, who kerp piranhas and and he was issuing 50 times flow!
He seemed to be having succeed but he did not stay around very long...


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## darren636 (2 Oct 2014)

Perhaps the piranah took him....


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## Andy Thurston (2 Oct 2014)

foxfish said:


> There was chap about a year ago or so, on this forum, who kerp piranhas and and he was issuing 50 times flow!
> He seemed to be having succeed but he did not stay around very long...


He wasnt growing hard plants under bright lights either


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## Jaap (2 Oct 2014)

If the plants arent uprooting does high flow still cause problems?


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## foxfish (2 Oct 2014)

I don't know but to my eyes it look pretty obvious if the flow is to much, so from an aesthetic point of view I would say really high flow is not good!
Gas exchange will be high so possibly a higher injection rate might be required..


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## drodgers (12 Oct 2014)

I've been looking at a lot of plants we keep in there natural habitats via oline sources I've come to the conclusion that good water movent is essential in the aqurium.


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## parotet (13 Oct 2014)

Hi all

Lately I have been watching much more planted tank videos than pictures. This is because in just a few seconds you can understand/see much more things compared to a picture. If you watch any successful planted tank video you will see that flow velocity is sometimes strong and sometimes not at all… so why this?

Well, IMO a planted tank is like a complex equation in which there are a lot of interdependent variables. In our narrow-minded vision on planted tanks, we try to fix some reference values for each of them, but the fact is that it is much more complex than that. Once again IMO it is much wiser to pay attention to the variables which are more important on the final result, so you can focus on them.

A vast majority of the questions in forums are something like “is this light good?”, “is that flow ok?”, “is that fish stocking ok?”, “is that fert dosing ok?”, etc. (or just a help call when things went wrong, something like “how can I get rid of this algae…” which of course is more or less the same kind of question). And the most sincere and best answers are the ones saying “well, it depends on…”. But we don’t like these kinds of answers, we still prefer someone saying: if you have X problem, the solution is Y. For that tank volume you need X light, Y flow, Z ferts…

So, as you may be expecting now, my answer is: there is enough flow when the rest of the parameters are good enough. In other words, if your Co2 is perfect for the light you have, plants have enough ferts, you have the right plants for your setup, you have good and active growing, your filter turnover is enough for this particular configuration, you have loads of plant biomass (and add here whatever you already know from this forum), your flow velocity would be ok.

I guess there might be a kind a threshold/rule of thumb for flow, as there is for example for filter turnover, but once again someone will say “I run a tank like this with half the value you are mentioning…”. Of course use also common sense: blowing your plants and substrate is not a wise option, so there you have what you don’t want as flow velocity. Below this, well, it depends on… 

Jordi


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## drodgers (13 Oct 2014)

parotet said:


> sometimes strong and sometimes not at all… so why this?


I lot of people remove their spray bars etc to do the video is the my thoughts but im sure their are some low flow tanks out there i know some people do daily water changes ?


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## Jaap (19 May 2015)

Is there a chance that high flow will cause brown algae in the sense that it will not allow bacteria to attach easily on surfaces?


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## Marcel G (19 May 2015)

parotet said:


> HWell, IMO a planted tank is like a complex equation in which there are a lot of interdependent variables. In our narrow-minded vision on planted tanks, we try to fix some reference values for each of them, but the fact is that it is much more complex than that.


Although I like what Jordi said, I put my two cents in this discussion.
According to one study there can definitely be such a thing as too much CO2, as in this study after the CO2 concentration exceeded 40 ppm, some plants begin to suffer, and their growth rate degraded a lot. The author of this study concluded that this high CO2 concentration may "poison" some plants.

As to the flow, we all probably know that the higher the flow the thinner the boundary layer and the better the nutrient uptake rate. So higher flow means better growth for most aquatic plants. I would add that as long as the plant is able to control the position of its leaves toward the light source, the flow is OK. So the flow is too high whenever the leaves cannot turn toward the light anymore, and are just carried by the strong flow which they are not able to resist. So plants need for their leaves to be directed toward the light, so if the flow is too high, the leaves are not able to collect photons efficiently enough, and they begin to be stressed. (Vallisneria is maybe an exception, as its leaves are long and can float on the surface, so even in the very strong flow it can collect light quite efficiently.)


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## Jose (19 May 2015)

ardjuna said:


> Although I like what Jordi said, I put my two cents in this discussion.
> According to one study there can definitely be such a thing as too much CO2, as in this study after the CO2 concentration exceeded 40 ppm, some plants begin to suffer, and their growth rate degraded a lot. The author of this study concluded that this high CO2 concentration may "poison" some plants.



Is there any possibility that you could link this study Ardjuna?


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## sciencefiction (19 May 2015)

As Troi stated, too much flow can cause mechanical damage.
I had a powerhead blowing at a big anubias. The leaves that were near it got destroyed and that plant has thick leaves. I don't want to imagine if it was a delicate plant. But I am talking about a 2800l/h powerhead.
I now have an internal filter(1000l/h) in one tank that blows at an amazon sword directly. Most leaves become a mesh and get literally washed off...
And if you are fighting algae on top of it, them blown leaves are the first to get it. So yes, there's is such a thing as too much flow, especially if the flow is pointed directly at the particular plant and is not diffused first via the glass.
However, I am not sure if it will stop them from growing, but they won't look good for sure.


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## Marcel G (19 May 2015)

Jose said:


> Is there any possibility that you could link this study Ardjuna?


https://dl.dropboxusercontent.com/u/8272114/akva/knihy/1985_Cizkova_Photosynthetica.pdf (brief English version)
https://dl.dropboxusercontent.com/u/8272114/akva/knihy/Cizkova_Studentska_vedecka_prace (orez).pdf (complete Czech version)
Some of the data can be found (explained) here also: http://www.prirodni-akvarium.cz/en/rostlinyNaroky (seek "nearly poison").


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## Edvet (19 May 2015)

Plants can and will grow in high flow areas, just not all plants.


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## Jaap (19 May 2015)

How about monte carlo, stayrogen repens and hair grass?


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## kirk (19 May 2015)

Interesting question about too much flow. I been wondering this since set up as growth is very slow. 

I am using the same filter and korilina on this 60 ltr that I was using on our 120ltr.

If I was using cat litter it would be like a snow globe.


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## Edvet (19 May 2015)

I always take clues from Flowgrow or Kasselman, f.i. on Staurogyne they say: "The aquarium population of this species originates from Rio Cristalino in the Brazilian federal state Mato Grosso. The plant were found growing on and between rocks on the bank of the fast-flowing river, mainly above the waterline, and in full sun." They should be able to cope with flow, if they have plenty roots.
On the other hand most popular aquariumplants (from commercial growers) usually grow well emersed,,hence are more bogplants then real waterplants.


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## Tim Harrison (19 May 2015)

If it's high flow plants you're after have a look at this...http://www.ukaps.org/forum/threads/plants-that-like-strong-water-flow.34777/#post-372066


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## Jose (20 May 2015)

I think as has been stated before that: as long as plants are not being lifted from soil or being moved around violently then  flow isnt excessive. Maybe some mosses might not like higher current but thats about it. Also if a plant is being pushed around violently this doesnt necessarily mean that you have too much flow, it can also bee that you have bad flow distribution in the tank. But yes I still think in few cases flow can be excessive, specially from powerheads.


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## Ryan Thang To (21 May 2015)

When i had my 90cm tank planted with glosso it only grew upwards. I had a aps 2000l/h filter and 2 1600l/h hydor power head on each side. This was my first high tech and i was told it that its all about balance with co2 light and good flow. I was convince flow wasn't enough so got 2 power head. Here some pictures of my set up and what a change after lan holdich a ukaps member mention about my tank has too much flow. 


 


 
A few days after removing the power head


 
A week in and glosso is spread finally


 
A whole month carpet nealy complete


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## kirk (21 May 2015)

A whole month and a full carpet,go on rub it invthe don't you.


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## Ryan Thang To (21 May 2015)

kirk said:


> A whole month and a full carpet,go on rub it invthe don't you.


Haha trust glosso grow rate is really fast.


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## Andy Thurston (21 May 2015)

legytt said:


> Haha trust glosso grow rate is really fast.


your not wrong Ryan the glosso you sent me is nearly a full carpet already


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## Ryan Thang To (21 May 2015)

Big clown said:


> your not wrong Ryan the glosso you sent me is nearly a full carpet already


me too. I had them in just a bit a early than your


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## Andy Thurston (21 May 2015)

I've trimmed mine already to stop it taking over the tank, monte carlo is going crazy too. I'll try get some pics for the journal when the co2 goes off


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## Iain Sutherland (21 May 2015)

high flow can reduce growth in my experience.  Particularly in my 60 i find the slowest area to carpet or plants to flourish is around the diffusor where flow is highest.  Not sure why?  Possibly the flow is so strong the co2 is just whipping by?  Reduce the flow and those plants perk up.  Its a fine balance... as we speak my reinekii mini around the diffusor that was invitro and planted last week is shedding a few leaves but the rest of it is doing just fine elsewhere.  I try to think of it as turn over not flow... high turn over good - high flow not so great normally.


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## Edvet (26 May 2015)

Ah found the video i was looking for: to much flow??


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## sciencefiction (26 May 2015)

Ha, ha Edvert....

They look like they have a CO2 problem lol  And the water needs a bit of purigen to clear up the floating matter.....


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## Jaap (3 Jun 2015)

ardjuna said:


> Although I like what Jordi said, I put my two cents in this discussion.
> According to one study there can definitely be such a thing as too much CO2, as in this study after the CO2 concentration exceeded 40 ppm, some plants begin to suffer, and their growth rate degraded a lot. The author of this study concluded that this high CO2 concentration may "poison" some plants.
> 
> As to the flow, we all probably know that the higher the flow the thinner the boundary layer and the better the nutrient uptake rate. So higher flow means better growth for most aquatic plants. I would add that as long as the plant is able to control the position of its leaves toward the light source, the flow is OK. So the flow is too high whenever the leaves cannot turn toward the light anymore, and are just carried by the strong flow which they are not able to resist. So plants need for their leaves to be directed toward the light, so if the flow is too high, the leaves are not able to collect photons efficiently enough, and they begin to be stressed. (Vallisneria is maybe an exception, as its leaves are long and can float on the surface, so even in the very strong flow it can collect light quite efficiently.)



If it "poisons" plants, however fish seems to be fine, is there a chance that useful bacteria get "poisoned" as well which in consequence causes diatoms?

Also can diatoms be produced without the presence of fish and their waste products?

Thanks


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## Jose (3 Jun 2015)

Jaap said:


> If it "poisons" plants, however fish seems to be fine, is there a chance that useful bacteria get "poisoned" as well which in consequence causes diatoms?


I highly doubt it. What happens in tanks where people keep very high co2 levels and no fish. They wouldnt get rid of diatoms yet most dont have it. 


Jaap said:


> Also can diatoms be produced without the presence of fish and their waste products?


Yes for sure. Fish arent actually the main source of waste in many high tech tanks. Its plants.

Also I would just like to say one thing. The link Ive read for the study where the conclusion made by some is: high co2 (over 40ppm) can kill plants has to be taken with a pinch of salt. This is not totally true/ not always. What they say is that for a certain weed at a pH under 7 (If I recall correctly) the higher co2 levels can kill the plant, but not for higher pHs. This is a very specific situation and shouldnt be extrapolated to saying that 40 ppm of co2 can kill most of our plants. This doesnt happen and the opposite does. The more co2 the better most plants grow, specially the harder ones.


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## Marcel G (3 Jun 2015)

Jose, no one (or to be specific: not me nor the author of the study) said that higher CO2 concentration will _*kill*_ the plants. What the author said is that the concentration of 1 mM CO2 (= 44 ppm) caused rapid _*decrease of growth*_ in the studied plants. When I spoke personally with the author she told me that she explains it to herself as a kind of "poisoning effect" (as if too much CO2 somehow "poisoned" the plants). Also, no one says that all plant species react to elevated CO2 levels in the same way. But for sure there are at least some plants which don't prefer high CO2 levels. Each plant has its optimal growth under different conditions. What I wanted to say is that we should be aware of it, and don't repeat blindly that we need 40 ppm of CO2 or even more. Also the author of this study concluded that the difference in growth was definitely caused by the elevated levels of free CO2 and not by the pH. I have the whole work in Czech language (the article in English is just abbreviated version). Also I'm in contact with the scientist (author of this study).

What I can confirm from my own experience is that diatoms really don't need too much organic wastes to prosper. Once I had a test tank where I had about 150 ppm NO3 and quite high levels of other nutrients leaching from the substrate bottom layer packed with a fertilizer (you can look at it here => Test #3). I did some laboratory analysis of my water, and there were nearly no organics in it, but high level of inorganic nutrients. Also I did not used any CO2 in this tank, just Excel. The tank was under "high light" (100 µmol PAR). All other algae as well as cyanobacteria just died after two weeks of bloom. The pH went down to 5. The redox values were extra high (above +500 mV), and were constantly increasing. The only visible organism that survived in this hostile environment were diatoms. I suspect that even the useful bacteria had to stop working in such an environment. Diatoms seems to be immortal.


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## Paulo Soares (3 Jun 2015)

Each tank is a tank.. each experience is a experience.. mother nature is not an exactly formula. 

I notice that in my tank the area with less flow is the one under the outflow and plants there doesn´t grow so fast as all others..
So according to this i would problaby say that less flow equal to less growth ins´t that so?. 

But than again we would have to measure all variables mentioned by "Parotet". 

Concerning the CO2:
In my opinion for what i was able to observe in my tank along the time, high levels of Co2 does harm the plants. 

Without changing any other parameter i only downgrade the Co2 and notice plants to be having a more colourful aspect and robust stalk cause they are not growing so fast. 
There was a more sustainable growth. If you increase to much CO2 (macro nutrient) is just like if you do ignition on an engine and pump the gas without letting the engine to warm up and lubrificate all engine parts so that you could take an 100% profit from it. Get the Picture?

You can have the light you want or uptake Ei fert as much as you like and so on but it all leads to Co2 as this is the ignition for plants to assimilate the rest.

So here yes.. i assume CO2 as the major factor for a sustainable growth. 

And finnaly.. doing the mental exercise in inverse we came to the the initial issue: The flow! 

In order to have a very good Co2 dissolution in the tank, yes you´ll need good flow! Not faster.. Good flow is: efective/eficient/ and this doesn´t mean outflow velocity ou filter pump capacity liter /hour. 

Another thing, you´ll probably also need to figure out (testing) what hardware positioning gives the best result. And for measure that is not a question of days but weeks.. be patient.
Assembling and being a day watchfull hobbiest to see improvements or not.  

Notice: Seeing bubbles of CO2 going around the tank is not a good guide to assume a good efective flow or CO2 dissolution as so many people think it is. If you see to much bubbles maybe you should consider changing your Difuser also. 

Regards.


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