# [Wet Thumb Forum]-What promotes algae growth?



## imported_aspen (Feb 20, 2003)

roger, i have been reading these forums etc for a couple of years, and the one thing i have decided about algae growth, is that no-one really knows why algae grows in one tank, and not another. in my own experience, i have tried all of the theories, and have discovered a few things about algae. 

algae will take off in a new tank, if given half a chance and some fertiliser, regardless of which nutrients are added, or in which ratio. after some time, and a few algae bouts, the algae seems to just go away. that is, provided you give the proper light, co2 and nutrients to grow plants, gradually. this seems to take 2- 4 months, depending on light, co2 nutrient levels, and number of plants you start with.

one other thing i've noticed, is, that while algae will grow on the glass and the substrate, the leaves of the plants, usually in the area of most intense lighting will usually be much more algae free. logically, there should be more algae on the leaves of the plants in the higher light areas, than on the substrate, but there you go.

there are more questions than good answers about how to grow algae, or how not to.

i starve a tank to start with, start with hygro polysperma, etc and slowly ramp up the fishload and the growth of the plants. then swap in nicer plants as the tank matures. it works for me.

rick


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## Roger Miller (Jun 19, 2004)

I thought that aspen's post to an earlier thread raised an interesting question, so I'm using it to branch a new topic.


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## Roger Miller (Jun 19, 2004)

I thought that aspen's post to an earlier thread raised an interesting question, so I'm using it to branch a new topic.


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## Roger Miller (Jun 19, 2004)

Rick is right. After years of questions and answers about how to *prevent* algae growth I think our best answer is simply that good plant growth appears to suppress algae. Maybe if we can get further if we take a different angle.

What factors promote algae growth over plant growth? The answer certainly must vary with the kind of algae in question. 

In my tanks:

1) New tanks are prone to problems with a lot of different kinds of algae.

2) Short term declines in CO2 levels and moderate light levels promote diatoms

3) Low light promotes red algae growth over plant growth, and extra CO2 in the system produces a *lot* of red algae growth.

4) My tanks get a kind of soft, dark green hair algae that grows among plants in shaded areas with poor circulation.


Roger Miller


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## Wheeler (Feb 8, 2004)

I find the opposite of what Aspen relates:

When I start a new tank, I begin, from day 1, with nutrients at 100%. I don't see any algaes untill the 2-4 month....Then slowly the little threads and green spot show up, then BBA after the 4th month or so.

BBA is the only algae that I seem to be able to grow with any sort of abundance. I blame my tap water.

I have, recently, scaled my fert dosing WAY back, and that seems to be to the benefit of plants, and dismay of algaes. I had always just assumed that a surplus of input (ferts, etc) and a deficit of output (plant growth, water changes, etc) were the primary cause for algaes. I think that I might be paraphrasing Arthur Westover there. Seems logical enough to me and congruent with my experience, though Van Grow will surely dispute this..... I don't know how he runs his tanks so rich with out problems.









Are the requirements of algaes that much different than higher plants?

Best wishes,
John Wheeler


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## imported_Allen (Feb 14, 2003)

This is quite true... we had a similar long discussion in our local forum and ended up concluding that even the "experts" don't really know for sure how algae ticks...

We ended up giving a general rule of thumb

Healthy Plants = Less Algae... thats about all that could be said.

As for my own tank, I've had experience with 4 kinds of algae

1) green spot algae... which has plagued me since the start of my tank... Incidentally, has anyone noticed that spot algae grows much better in areas of poor circulation?
2) brown algae... none in my tank itself, but in my reactor and filter pipes. Speaking of which, a friend of mine tooks some snails, and put them in his reactor... he then sealed the reactor with a fine netting which prevented the snails from leaving... since then his reactor has been spotlessly clean.
3) BGA during the period when my daughter was born and my tank got badly neglected for several months
4) A green bushy algae which clings to my backing... So far its not an issue and I quite happy to mechanically remove whats there when I do a water change.

Allen 
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Allen's Tank Pics.
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## imported_aspen (Feb 20, 2003)

how to grow algae: add nutrients and light, and there you go, algae, seemingly right out of thin air. i believe the q is, 'what inhibits algae'. algae rarely grows on leaves that are thriving. it will almost always grow on my substrate.

people talk about the theory that plants will 'out-compete' algae. that is bunk. in a tank with consistent raised levels of nutrients, there is no out-competing going on here. there is food and light enough for all. we try and make our tanks a perfect place for plants to grow, yet algae seems to be inhibited. by WHAT?

there is a process going on in a tank, which allows 'the plants we like' (or something else possibly) to inhibit 'the plants etc we don't like'- the algaes and bga. when we discover what that is, we will be in the position to easily inhibit algae, while having thriving plants. no theory i've heard to date answers this question.

rick


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## Roger Miller (Jun 19, 2004)

The question was "What promotes algae growth over plant growth" not simply "how to grow algae'. Light+nutrients grows both plants and algae, so by themselves they don't answer the question.

I have a unproven theory that algae growth is promoted by nutrient-deficient plants. This is the flip side of the idea that algae are suppressed by healthy plants.

Many algae are capable of heterotrophic growth, using simple sugars in solution in place of their own photosynthetic products. Claus Christensen considers it to be proven that blue green algae can use organics from the water. He wasn't so agreeable that green algae could do the same.

Plants leak metabolic products and (again according to Claus) raw nutrients into the water. There is published speculation that the leakage of metabolic products is an evolved-in mechanism. Aquatic plants leak metabolites to promote algae growth on their leaves. The idea is that herbivors graze on the algae growing on their leaves rather than on the leaves themselves.

I reason that plants that are nutrient-limited will leak even more metabolites. Nutrient-limited plants receive sufficient light and CO2 to fix carbon into simple organic molecules, but they are missing one or more of the nutrients they need to process the simple organics into more complex molecules. I expect the products to build up until they are lost into the water. I think it has been shown that nutrient-stressed algae will leak metabolites. The idea that plants will do so is my speculation.

We have whole classes of algae and blue green algae that thrive in aquaria under conditions of low light and low circulation. I think those algae may thrive in aquaria because the plants promote their growth. Stop the plants from promoting their growth and the algae will go away -- or at least fail to thrive.


Roger Miller


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## imported_Allen (Feb 14, 2003)

Roger,

I read a previous posting of yours with great interest (now archived) about a conversation between Claus christenson to Cavan Allen... If I remember correctly, you were talking about DOC.

This got me thinking... would the introduction of enzymes which help break down water borne organics help in the battle against algae. I know nutrafin sell such a product.

To be honest though, my own understanding of DOC is severely limited... Its still uncharted waters for me.

Allen 
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Allen's Tank Pics.
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## Vicki (Jan 31, 2003)

> quote:
> 
> green spot algae... which has plagued me since the start of my tank... Incidentally, has anyone noticed that spot algae grows much better in areas of poor circulation?


No, I sure haven't. In my tanks it is exactly the opposite; green spot algae thrives only in areas where water circulation is high. In my 120 gallon, the barteris that are planted close to the filter outflow (and most particularly the leaves that are directly in its path) tend to become covered with green spot algae very quickly, even if they're new leaves. Leaves lower on the plant that are out of the flow (and also,it should be noted, much more shaded) don't accumulate near as much. I find the same to be true in my 55 gallon.

Green spot algae is pretty much my only issue, and it never grows on the glass--it's almost totally confined to anubias leaves. Once in a while I'll notice some on an E. tennellus leaf, but it's almost always a leaf that's dying anyway.

I too have gone through the assorted algae plagues in new tanks, but when I set up my 120 last June, I went full bore with lights, CO2 and fertilizers right away and filled the tank with fastgrowing plants. I had a watersprite thicket you wouldn't believe, and I never saw any visible algae of any kind except for a smattering of brown and green dust algae on the glass--no more than you'd expect to grow between water changes and glass cleanings. I'm sure the six young SAEs that were the first fish in the tank had a lot to do with that also. After about four months, I began replacing the fastgrowers, and removed the watersprite altogether; except for the green spot algae I mentioned above, I've had no problems. I was hoping that would begin to disappear as I began dosing phosphates, but so far it hasn't; the levels are never higher than .5, and closer to .2 most of the time, maybe I'm just not dosing enough. Anyone have any suggestions?

http://www.wheelpost.com


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## Roger Miller (Jun 19, 2004)

Vicki,

Green spot algae was the bane of my anubias when I grew them in a low light tank with no added CO2. At that time I'd even get green spot on the glass.

I'm pretty sure that there isn't a real good correlation between low CO2 and green spot on anubias, as I've grown A. barteri nana in nearly full sunlight with pH over 9 without green spot, and the nicest, cleanest coffeeafolia I've ever seen came from a rift lake tank with pH always over 8.

I get green spot now and then in two different aquariums; on Anubias barteri nana in one tank on Saururas cernuus in two tanks. One tank is a low light tank and the Saururas is very slow-growing. The Anubias in that tank grows OK, but gets green spot on older leaves. The other tank is moderately lit, but green spot shows up when the DIY CO2 level drops and growth slows down.

In my experience, green spot algae is always more prevalent on leaves then it is on glass, and it's only a problem on certain plants. I'm going to guess that there is something about the surface of certain leaves that the green spot finds favorable. The plant itself produces conditions that are favorable for green spot. To get rid of the algae you have to get the plant to change.


Roger Miller


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## wetmanNY (Feb 1, 2003)

I feel like I'm witnessing the New Plant Physiology right here!

If we could drop "blue-green algae" and call them "cyanobacteria" it wouldn't just be owlish correctness: it would help remind innocents like me that not all photosynthesizers are either plants _or_ algae. So though Claus Christensen considers it proven that cyanobacteria can use dissolved organic carbon, we wouldn't conclude that any _eukaryotic_ alga, green or otherwise, could _necessarily_ do the same.

I'm confused by Roger Miller's statement "Many algae are capable of heterotrophic growth, using simple sugars in solution in place of their own photosynthetic products." Is this a question of fermentative processes within the cell, or a question of "growth" of the organism in the sense in which laymen understand "growth?" Are these sugars absorbed from the exterior environment across the stiff algal cell wall, somewhat as fungi absorb them? So the addition of glucose to the aquarium would spark an algal bloom? Nothing I'd even considered before now!

I guess we're all rather "leaky" organisms, even us land mammals, who have evolved so may ways to preserve our hydration-- not such an urgent concern with aquatic plants or algae. I do like the idea that aquatic plants leak metabolites _to_ promote algal growth on their leaves. A purposive vision of processes guided by a Benevolent Will. Something you either feel, or you don't.

Aquatic ecologists, though, usually suggest that there's much less herbivory actually going on in freshwater ecosystems than we envisage in our well-planted aquaria with Melanoides snails and algae-eaters. All that planning for epiphytic growth, and then so few takers...


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## Guest (Mar 7, 2003)

If you add algae to a tank and add nothing but tapwater, you will get algae.
Leave some sand outside,add some water regularly, you will get algae.

I do not think weak plants are feeding the algae. I think algae knows when someone else is there.

I need to do the O2 thing and I'll know pretty good. Remove the plants but add the O2.

See what happens.

Adding CO2 should reduce photorespiration in algae in theory, but a number of algae are programed to grow using HCO3. 
They need to use a fair amount of energy to do this. When this excess energy is no longer being used, this backs up the photosynthetic machinery.

Algae fry themselves with an overload they are not used to. Plants on the other hand are fine with the CO2 and are use to photorespiration.

Adding O2 only makes this issue even worse for the algae. This causes the CO2 fixing enzyme RUBISCO to increase it's bifunctionality by fixing O2 instead of CO2. Algae also try their best to concentrate the CO2 arounf the enzyme and reduce the O2, but if there's lots of O2 present, the algae may genetically down regulate their growth and go into a rest phase/form tough gametes/spores etc.

I like Blue Green algae. Phycologist and Botanist have done most of the work on the group. They named it that and that should stick. When microbiologist have done 50% of the research work then they get to call it what they want. They have a long way to go still.

But as far as an approach to getting rid of algae, healthy plants is the way. If the plants are not growing, the algae will.

Low O2 level might encourage algae. Poor plant growth etc.

Regards, 
Tom Barr


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## Vicki (Jan 31, 2003)

> quote:
> 
> The plant itself produces conditions that are favorable for green spot. To get rid of the algae you have to get the plant to change.


Hmmm...therapy, maybe? Of course, then I suppose the plant would have to WANT to change...









But seriously folks...it DOES frustrate the heck out of me. I have no doubt that you're right about the plant encouraging green spot algae growth, Roger, I just wish I could figure out how to break the cycle. I guess I'll follow Tom's earlier suggestion and trying upping the phosphates some more and see what happens.

http://www.wheelpost.com


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## tsunami06 (Feb 6, 2003)

Algae growth for me is a given when I first
setup a tank. I have noticed that one of the
biggest reasons I have algae outbreaks is
instability (such as a broken CO2 reactor,
medications for the fish, forget to add
iron then start adding it again a month
later, adding fish to a new tank, etc).

Lately, this instability has made me face
an algae I've never had to deal with before:
Cladophora. It seems to attack only old,
weakened leaves and doesn't bother new
growth. Staghorn algae is another new one
with the same habits as the Cladophora. The
moss is especially suffering. Conditions
in this tank for the last two weeks?

PO4: 0.5-1.0 ppm
NO3: 5-10 ppm
CO2: 20-30 ppm
3x5 mL Flourish Iron, 3x5 mL Flourish Trace
3.95 w/g of light on a 20 long...

Apparently, nothing wrong. However, due to
my inability to keep some stability in the
tank for two months (3 week vacation and the friend didn't add the Fe/traces, then a broken CO2 reactor, then the fish got ich, and then I had to medicate...), I've had slowly
recovering plant growth and slowly receding
algae.

Other algae:

1) green water, once the bane of my existance... my 55 gallon is notorious for
being rescaped and then attacked by a bout
of green water for 2 months afterward. After
trying everything to stop it twice, it just
went away by itself, probably due to strong
plant growth. Lately, I just use my micron cartridge + flocculent to blast it.







It
does come back, but the light levels
reaching down to the plants with the use
of a micron catridge shortens the length
of time I have green water (i.e. two weeks
instead of two months).

2) blue green algae -- tons of it! When I
increased my lighting on my 55 gallon to
3.75 w/g PC, I didn't increase the efficiency
of my CO2 system. Fixing my CO2 system helped
a lot. I had a less virulent variety attack
about six months later along with some
brown dust algae. I increased my PO4 dosing,
and it went away within a week.

3) I do get the green dust/spot algae on the
glass. However, it also eventually fades away
after a few months. I never seem to get any
spot algae on my Anubias nanas though. I have
some directly under the light and others
in the shade.

Motto: give the plants what they like and
try to keep their nutrients/CO2/light in a 
steady, stable supply = less to no algae.

Carlos


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## wetmanNY (Feb 1, 2003)

I'm struggling to piece together a coherent logic in these posts, but I do feel sometimes like Tom Barr's memorable algae, that "fry themselves with an overload they are not used to."

About green spot algae: I see from reading Vicki's post that this kind of algae thrives for her where water circulation is high. I can't tell whether this filter outlet flow is where CO2 levels are highest from dissolving CO2 bubbles drawn into the filter, or whether the path of the outflow is where O2 is highest, as it would be in my tanks. owing to surface turbulence and splash. 

Is the gist, then, of Roger Miller's following post, that CO2 levels are essentially irrelevant to the presence/absence of green spot algae? That he's seen clean leaf growth in high pH situations (where CO2 would be all in its carbonate/ bicarbonate phases) --yet that it also shows up when the DIY CO2 level drops.

Is the consensus here simply that certain leaf surfaces such as Anubias offer a better substrate for this alga than slick glass does, that it shows more as leaves age, and that where CO2 levels are low it may equally thrive or not be present at all? If that's it, then I get it.

When tsunami notices that algae outbreaks follow upon instabilities, for an example, medication of the aquarium, I'm reminded again how consistently we tend to overlook the role of freshwater zooplankton in the natural control of green water algae. "After trying everything to stop it twice, tsunami posts, " it just went away by itself." Very telling, I feel.


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> Is the consensus here simply that certain leaf surfaces such as Anubias offer a better substrate for this alga than slick glass does, that it shows more as leaves age, and that where CO2 levels are low it may equally thrive or not be present at all? If that's it, then I get it.


I doubt there's any consensus, but I think you get it anyway.











> quote:
> 
> When tsunami notices that algae outbreaks follow upon instabilities, for an example, medication of the aquarium, I'm reminded again how consistently we tend to overlook the role of freshwater zooplankton in the natural control of green water algae.


Bacterial and viral phages may also play a role. I'd like to think they work on attached algae as well as on green water.

Roger Miller


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## ck (Jun 6, 2004)

> quote:
> 
> Originally posted by Van grow:
> They need to use a fair amount of energy to do this. When this excess energy is no longer being used, this backs up the photosynthetic machinery.
> ...


This is very interesting, cos in bacterial fermention reactors, the excess of glucose leads to an "metabolic overflow". From what I understand, in an attempt to use the available energy source as quickly as possible, they do it rather inefficiently and the cells end up producing lots of lactate, citrate, acetate. The build up of these acids kills/lyse the cells. Could there be a similar mechanism in algae?
Could it be that in the abundance of CO2, nutrients, algae grow too well and fast that they do themselves in? It seems to fit the model that a limiting parameter, say CO2 or N, cause growth of algae, but abundance of everything, slowly kills them. Plants OTOH, probably handles the surge better and grows wonderfully. Also CO2 seems to key to drive them over the edge.

Think about it... you try to stave algae, it just grows better... if you try to grow it, it dies on you. 

Maybe the other water parameters such as water circulation, light, pH, alleopathy are secondary factors that determines what type of algae grows where.

ck
Sunny Singapore


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## wetmanNY (Feb 1, 2003)

Thanks, Roger! That's _almost_ like "Yes, you're right!" I think the planktonic role of bacteria is limited by the density of the drifting floc and detritus, which they use as a substrate. Only in labs are bacteria likely to be living free, in a nutrient broth. But bacteria do feature prominently in the biofilm that covers every matured submerse surface, whether the substrate is organic or inorganic.

"The ecology of viral phages in the aquarium" --now _there's_ an untrammeled subject!

ck! does "metabolic overflow" also apply to the metabolism of yeast in DIY CO2 canisters? Boosting sugar content, as newbies are tempted to do, might be metabolically counterproductive. And the gelatin technique, which keeps yeast from getting at all the sugar at once, might keep the yeast metabolism more thrifty, with fewer toxic metabolites.

--Genealogically, yeast and algae are similarly distant from bacteria, of course.


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## imported_aspen (Feb 20, 2003)

>>'...for an example, medication of the aquarium, I'm reminded again how consistently we tend to overlook the role of freshwater zooplankton in the natural control of green water algae...'

yes, i have often wondered if the smaller inhabitants of our tanks was responsible for the biggest job of cleaning algae. i treated a clean, established aquarium with formalin and it immediately went into an algified mess, and was torn down.

in my successes with planted tanks, in the ones where i weathered the storms and came out the other side, there always seemed to be 'a day' when the water clarity was striking. that was the day that i stopped fighting algae, and started having fun, and all was well. i haven't had all that many planted tanks running, not as many as some here, but when i start, i take care with every fish, plant placement, and light change, then one day, the algae wouldn't grow if i wanted it to.

one thing i have always done from the beginning though, is to pp all of my plants,to ward off snails, and clean my substrate fully with chlorinated water. maybe i am 'hooking' myself with this practice in the beginning stages, but i have to admit, snails are never a problem, nor is hair algae since i started doing this. staghorn or some of the other types people talk about in frustration have never been a concern since i started doing this, when i heard that a lot of types of algae MUST come in with the plants or they won't be in the tank.

could it be, that the plants, when growing well, give off substances that inhibit algae, AND a miniature eco-system needs to be established, to inhibit the 'plants we don't like'? and, by treating our plants, we are killing the micro-inhabitants which need to re-grow to find their food supply. btw, what are fry eating, when they survive in a planted tank? are these things in ready supply in an established tank, similar to placing a lettuce leaf into water and letting the infusoria grow? generally, if you leave food out, somebody will come along to eat it eventually.

rick


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## plantbrains (Mar 11, 2003)

I have never dipped or quarintined my plants in any way other than rinsing the dirt off etc.

I routinely get plants from the wild.

I don't buy the allelochemical notion. At least not in tanks where CO2/regular water changes are done.

While zooplankton can be important in ecosystems, I think they play less a role in this. Most tank samples I have looked at under a microscope that are thriving have virtually zero zooplankton and I believe it's like the allelochemical notion, not much.

Most of these possibililities are drains on the O2 or increase the COD/BOD.

I know that reducing drains on O2 help in all cases and observations I've done.

I also know that low/delcining O2 levels are associated with distrubing the substrate and pulling up all the organic matter. Doing a water change right after improves the growth rather than if you left it alone.

I can add the same nutrients into the water column without issue except for NH4.

So I believe it's O2 and NH4. Which? Probably some of both.

Bacteria is another story, the substrate and biofilms on surfaces/filter etc.


Well, I'll soon find out when my O2 tank arrives.
I'll see how it effects a number of sporulating algae speices and then measure their growth rates at several typical environments(high CO2 and O2, low O2 high CO2, low O2 only, low CO2 only, etc) found in nature/planted tanks.

I think photorespiration is perhaps the largest factor in declines of algae. In order to increase PR in algae, the slight way is using CO2 but a much more destructive way for algae is increasing O2 levels.

Also, lower metaboism rates in cooler water and the ability for cooler waters to hold gases like O2 and CO2 may help some systems. 

Those are questions for later though.

But isolating the algae and using the O2 gas rather than a by product of higher plant production should remove the potential interferences. 

Regards, 
Tom Barr


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