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I don't get why increasing macro-nutrients helps defeat algae. Macro is NPK right? Maybe this is because I did a reef tank a long time ago but I thought the whole idea was to limit these to as near zero as possible so only the good stuff would grow.

I would think that adding these would cause an algae bloom, not stop it.
 

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in the planted tank the idea is to limit algae by promoting plant growth.
we add macros to make the plants grow well, and with proper amounts of nutrients plants get the upper hand on algae.

algae still survives, its there just waiting for me to screw up. :wink:
but I cant see it, and most of the time algae doesn't bloom as long as the plants are healthy.
then theres green dust algae..
 

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in the planted tank the idea is to limit algae by promoting plant growth.
we add macros to make the plants grow well, and with proper amounts of nutrients plants get the upper hand on algae.

algae still survives, its there just waiting for me to screw up. :wink:
but I cant see it, and most of the time algae doesn't bloom as long as the plants are healthy.
then theres green dust algae..
Still doesn't make sense to me. If I had 57 picnic lunches (nutrients) and I dumped them all over the ground. Lots of happy people (the plants) could pick them up and eat like crazy but the ants (algae) could get as much as it wanted.
 

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Still doesn't make sense to me. If I had 57 picnic lunches (nutrients) and I dumped them all over the ground. Lots of happy people (the plants) could pick them up and eat like crazy but the ants (algae) could get as much as it wanted.
But in the case of plants vs algae, the plants are more efficient at getting the nutrients, so the algae does not get fed. You just have to make sure the "lunches" are well-rounded meals. For instance, if you go too lean on Phos, then the plants will leave 'crumbs' behind and the algae will gobble them up.

-Dave
 

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Still doesn't make sense to me. If I had 57 picnic lunches (nutrients) and I dumped them all over the ground. Lots of happy people (the plants) could pick them up and eat like crazy but the ants (algae) could get as much as it wanted.
a suggestion would be to try it. read up on what dosing regime is recommended by biomass and lighting. Add adequate CO2, and flow to a planted tank. You'll see that it is a valid strategy and can also be extremely stable if the maintenance routine is consistent.

you do not need chemical filtration, you do not need to regularly limit nutrients by extracting them from the water column. Believe me, this hobby has already gone through many cycles of 'limit nutrient x' over the years and the results are not as pleasant as just letting the plants have what they need, keeping the tank clean and watching the results. The idea still pops up occasionally, especially in the limiting of phosphate to fight/prevent algae.

freshwater systems have different needs, and reefkeeping methods while completely valid in a reef do not necessarily transfer into planted aquaria. The things that we limit in a reef are things that are needed in a healthy planted tank.
 

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I don't get why increasing macro-nutrients helps defeat algae. Macro is NPK right? Maybe this is because I did a reef tank a long time ago but I thought the whole idea was to limit these to as near zero as possible so only the good stuff would grow.

I would think that adding these would cause an algae bloom, not stop it.
It seems to me the assumption was that due to the lack of macro-nutrients, plant cannot use other nutrients in the water. Those left over nutrients then cause algae bloom. By adding macro-nutrients, plants can take up the left over nutrients. Thus, stop or prevent algae bloom.

But I would think that if there is no left over nutrients, the added macro-nutrients will themselves become left over which will then cause algae bloom.
 

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It seems to me the assumption was that due to the lack of macro-nutrients, plant cannot use other nutrients in the water. Those left over nutrients then cause algae bloom. By adding macro-nutrients, plants can take up the left over nutrients. Thus, stop or prevent algae bloom.

But I would think that if there is no left over nutrients, the added macro-nutrients will themselves become left over which will then cause algae bloom.
Its possible that over-thinking the process causes algae bloom.
so I don't do it. no algae bloom! ;)

seriously, abundance within reason aids stability. If nutrients exist in great enough quantities in proper ratios to each other the plants will thrive. These ranges are wide enough to give us plenty of room to play with things like color, leaf shape etc. and still not have an algae issue.
 

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It is safe to say that abundance within reason aids stability. But how does one know whether the amount of macro-nutrients in a tank is abundant within reason? If one keeps dosing macro-nutrients whenever there is an algae bloom, there can be too much macro-nutrients ended up in a tank and therefore making things worse.
 

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It is safe to say that abundance within reason aids stability. But how does one know whether the amount of macro-nutrients in a tank is abundant within reason? If one keeps dosing macro-nutrients whenever there is an algae bloom, there can be too much macro-nutrients ended up in a tank and therefore making things worse.
thats true, but I wouldn't stick to a dosing schedule knowing I'm feeding a bloom. I'd change water / clean up and regain stability / return to dosing. probably also try to figure out where something went wrong. maybe it was dosing, maybe something else. flow / CO2 and lighting are also important.

for some ideas about 'abundant within reason' check out the write ups on PPS / EI dosing methods. There are also several posts here and elsewhere about ratios of macro nutrients in a planted tank. I manage my dosing by the ratio of KNO3 to KH2PO4, at around 5:1. Depending on the tanks grow rate and what I want to accomplish, I'll add up to 10-15ppm per day of NO3.

of course if I notice something drifting out of whack, I'll re-visit my dosing and adjust. After a while it gets easier to stabilize a tank at a desired growth rate. Or you can tweak dosing to get the plants to have a certain appearance. fun stuff, really.
 

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I was using Flourish and Kent Freshplant and Seachem's liquid macros, and I had algae and wasn't getting the results that I expected. I would change something and get an algae bloom, and it would make me afraid to fertilize. Then I got some dry fertilizers and a scale and took a deep breath and went for it. The results were astounding. Algae was reduced or eliminated, and some plants that looked fine but just didn't seem to get bigger, got way way bigger. Out of control bigger in some cases- a cool problem to have. Anyone want some water wisteria?
 

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Algae grow when there is a great chance that they can complete a growth cycle and reproduce. All other forms of life also expend most of their energy trying to reproduce. Aquariums have been around for perhaps 100 years, but natural water bodies have existed for something greater than 1,000,000 years. It should be obvious that algae evolved to be able to reproduce in natural settings, not in aquariums.

It appears that in natural settings algae and plants compete almost exclusively for light. Naturally growing aquatic plants tend to grow to the surface and cover it to get as much light as possible, while algae have to stay where they are, under the water surface. (Yes, this is a generalization.) In order for algae to have the best chance to complete a life cycle and reproduce they have to start growing when there are few aquatic plants growing, when aquatic plants won't be covering the water surface until after the algae have completed their reproduction. So, algae evolved to sense things that indicate that they will be successful in reproducing.

Two of those things seem to be the sudden presence of ammonia (dying plants and other water life?), and a drop in dissolved CO2 in the water (?). Once those things tell algae to start growing they will grow tenaciously until they finish what they are trying to do - reproduce. It takes very little nutrients for algae to grow, compared to plants. The consumption of nutrients is roughly proportional to the mass of plant or algae tissue. Algae, even when abundant, has very little mass, but plants have orders of magnitude more mass. So, algae don't need nearly as much of any nutrient as plants do.

Algae does not compete with plants for nutrients, because they don't need to. There are always more than enough nutrients for algae in our tanks. (Keep in mind that we are not discussing natural bodies of water now.) These things mean we should try to avoid any of the "signals" that tell algae to start growing. We know that ammonia will trigger algae to start, and we know that allowing the concentration of CO2 in the water to drop will also trigger algae to start growing. We also know that plants consume ammonia very quickly when it does appear. So, if we have a lot of fast growing plants growing, ammonia never exists in the tank except in very tiny amounts for very brief moments. That is why having a lot of fast growing plants, which means having adequate nutrients for those plants, is a protection against algae.

Is all of the above really true? Who knows? It is certainly an explanation that fits the known observations by a lot of people. So, it has a good probability of being true.

Natural bodies of water are another story entirely. Not all of those bodies of water have any aquatic plants in them. So, what triggers massive algae blooms there would likely be different. Other natural bodies of water have very little CO2 dissolved in the water - again algae blooms would be different. But, some natural bodies of water have both high CO2 content and lots of healthy plant growth - those should behave similarly to our aquariums.

There are at least thousands of different algae on earth. We face only a tiny percentage of those in our aquariums. What happens in nature may well involve algae types we never see in our tanks.
 

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How to combat algae?
Algae can not be starved to death, it goes dormant and waits. So how is it done?
Until today there is not much evidence to support any theory because few laboratories are interested to work on such insignificant market. However, most likely healthy plants produce chemical warfare and favorable conditions for beneficial micro organism which suppress and control algae development. So, if we think of it, it does make sense unless we go with some paranormal explanation. Now, the same applies to algae, if algae is thriving, plants are doing poorly despite any pro plants conditions. So yes, we need to feed the plants in order to get rid of algae or vice versa. Because we prefer plants over algae we need to feed the plants with elements plants are made of

C
Ca
Mg
N
P
K
S
Mn
Fe
Zn
Cu
Bo
Mo

That's all the elements plants need to grow healthy and keep algae under control.

Thank you
Edward
 

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Healthy plants release chemicals that inhibit algae. There are many different chemicals plants release to defend them selves. So if we go back to the food in the part the people eating are fighting off and stopping ants from coming. Just like we all do when we eat in the park stopping bugs and ants from getting our food before we do. The ei index shows this is true, ferts have a target level so as long as there is enough we must go to other things such as photo period and light intensity.
 

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I lack the chemical knowledge to dispute that "Healthy plants release chemicals that inhibit algae." But, I am almost certain it would be possible to test that theory. One way would be to take a large tank, say 125 gallon, plant it heavily with a big variety of plants, let it grow healthy and algae free. Then, take a 20 gallon tank that is having algae problems and replace the water with water from the big tank. If the theory is correct you can do this repeatedly and every time it will at least greatly reduce the algae in the 20 gallon tank. If it doesn't, you could do daily water changes using water from the 125 gallon tank - 6 days in a row - and that would stop the algae cold, if the theory is correct. Of course, good science would require repeating this many times, and always getting those results.

I am surprised that people have not set up "farms" to generate this chemical filled water, bottled it, and sold it for its anti-algal properties. The only reason I can see why they haven't, if the theory is correct, is that the chemicals being generated are so fragile and short lived that it can't be done. But, I have to believe Seachem or Tropica would be able to get around that problem.

This is not intended to be snark or a put down of that theory. I am just curious about why the relatively easy testing hasn't been done.
 

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I got this from Diana Walstad's book, I believe the correct name is allelopathic chemicals. From what I under stand caffeine is one of these chemicals that we are more familiar with. I am not in to the el natural personally but I read the book for it's scientific input. Just trying to put more pieces of the puzzle together. If you google allelopathic chemicals you will find a lot of info on them.
 

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I got this from Diana Walstad's book, I believe the correct name is allelopathic chemicals. From what I under stand caffeine is one of these chemicals that we are more familiar with. I am not in to the el natural personally but I read the book for it's scientific input. Just trying to put more pieces of the puzzle together. If you google allelopathic chemicals you will find a lot of info on them.
Yes, you can find a lot about allelopathic chemicals, but it is always about terrestrial plants, and only a few of them. I have never found any article about such chemicals coming from aquatic plants. Even Tropica did some work on that, but ended up saying aquatic plants probably don't produce them. http://www.tropica.dk/article.asp?type=aquaristic&id=531 Still, the test I mentioned should demonstrate that they are present, if they are.
 

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Your right there needs to be some tests. I'm sure that this is not the first time you have heard of this, has there been any research to try to back this up. As I said I read about this in a book, I'm starting to think I should question what I read more. I have also read that this explains why some plants do not grow with others. Do you think there is any truth to that?
 

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Your right there needs to be some tests. I'm sure that this is not the first time you have heard of this, has there been any research to try to back this up. As I said I read about this in a book, I'm starting to think I should question what I read more. I have also read that this explains why some plants do not grow with others. Do you think there is any truth to that?
Both Tropica and Tom Barr have said that allelopathy is not a factor in aquariums. That makes me think it very likely isn't a factor in aquariums. Where I have a hard time accepting that it is is that for such a chemical to be effective in retarding growth of either some plants or algae it should be easily detectable and capable of being synthesized. In other words it couldn't be so subtle that detecting it would be terribly difficult. I think it is obvious that once an organic compound has been detected it is always a pretty short time before it is also synthesized. Who ever synthesizes such a chemical stands to make some good money from selling it, so I am pretty sure it would have been done by now. However, that doesn't mean it doesn't exist, it just suggests to me that it doesn't exist.
 

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I lack the chemical knowledge to dispute that "Healthy plants release chemicals that inhibit algae." But, I am almost certain it would be possible to test that theory. One way would be to take a large tank, say 125 gallon, plant it heavily with a big variety of plants, let it grow healthy and algae free. Then, take a 20 gallon tank that is having algae problems and replace the water with water from the big tank. If the theory is correct you can do this repeatedly and every time it will at least greatly reduce the algae in the 20 gallon tank. If it doesn't, you could do daily water changes using water from the 125 gallon tank - 6 days in a row - and that would stop the algae cold, if the theory is correct. Of course, good science would require repeating this many times, and always getting those results.

I am surprised that people have not set up "farms" to generate this chemical filled water, bottled it, and sold it for its anti-algal properties. The only reason I can see why they haven't, if the theory is correct, is that the chemicals being generated are so fragile and short lived that it can't be done. But, I have to believe Seachem or Tropica would be able to get around that problem.
Plants adjust to their environment. A mere change in light intensity can cause the drastic action of discarding existing leaves and growing new ones. Therefore it is not that far-fetched for plants to release allelochemicals that are specific to the types and amount of algae found in the immediate environment. If that is indeed the case, moving the water to another tank (or extracting whatever compounds found in the water) may not work.
 

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Plants adjust to their environment. A mere change in light intensity can cause the drastic action of discarding existing leaves and growing new ones. Therefore it is not that far-fetched for plants to release allelochemicals that are specific to the types and amount of algae found in the immediate environment. If that is indeed the case, moving the water to another tank (or extracting whatever compounds found in the water) may not work.
definitely a stretch. I don't think that anybody who has debunked allelopathy believes that the effect is a myth, but that in the aquatic systems we keep its effect is negligible to the point of being a non-issue. It will be the least effective tool at our disposal, and thinking that we can leverage allelopathy to keep a clean healthy aquarium is wishful thinking at best.

now, I'm not a botanist or a scientific person so flame away on this opinion, and I dont mind at all. I have been keeping planted tanks for many years (as many of us here have) and have developed a common sense attitude towards what happens in these aquariums. I know that aquatic systems are incredibly complex, and aquariums being miniature aquatic systems have their own complexities -- but there are many ways to simplify what goes on there without sweating the details or looking for an explanation that is more convoluted than need be.

Fertilization when done correctly gives me healthy plants. And correctly usually just boils down to consistency in proper ratio. The ranges of acceptable nutrient levels are very wide, ratios are also forgiving up to a point. CO2, light, flow and clean water are the most beneficial tools I have for consistent health in tanks that can remain stable for many years. drop checkers / ph controllers / test kits / other stuff - not needed. I have not seen proof to this date that they are needed or even help more than a consistent maintenance and fertilization routine. drop checkers are one of the most misused and over-trusted pieces of equipment in this hobby.

One of the biggest mistakes I've made and continue to see others make is to overthink the processes in our aquariums and look for explanations or solutions that are less than obvious. I've learned that things like penac, tourmaline, and allelopathy (to name a few) are not to be taken seriously. Mainly because I have seen no true demonstration of their effectiveness in an aquarium that puts them above good maintenance / husbandry. Marketing hype does not count. keeping an 'open mind' is one thing -- false hope on unproven solutions is something else altogether.
 
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