# Do excess nutrients = algae? Is it possible to "know"?



## plantbrain (13 Jul 2010)

Some folks asked me about this this weekend. They suggested I cannot be 100 % certain that "Excess" nutrients do not cause algae. I mentioned: "I cannot test every cause of algae, thus I cannot ever be 100% certain. However, I can be virtually 100% certain of what *something is not*.  At least to point where consensus and general laws, patterns are easily accepted by Scientific standards".

Testing involves setting up a design to see if a hypothesis is tenatively true or false. 
We may never find the "truth" or be able to test every possible alternative to the cause of algae.
We can test individual and combinations of nutrients rather easily though.

Simply because a hobbyists has poor light or CO2 and doses nutrients = > algae does not imply the test is falsifies the hypothesis that excess nutrients does not = algae, they had confounding factors. This test does not enter into the statistical analysis. It must be redone and the test must be repeated.

If the hypothesis is excess NO3 or PO4 = algae, we must test the range of PO4 and/or NO3 to see. What is excess nutrients? Let's assume it's 20ppm NO3 and 5ppm PO4.

If we test a well planted tank with a good fish load, reasonable light, back up source of ferts in the sediment as well........this should be a good test up. For a control reference tank to be done, it must have no algae to start with.
It also must have ample head room for non limiting CO2. 

We can use "blocks of time" for test replications if we lack multiple tanks also. So each 4 week test period = one replication etc. After a few years, we have a lot of reps and a lot of statistical confidence if we never get an algae bloom. Other hobbyists then report similar long term results.

This suggest is CANNOT possibly be due to excess nutrients = algae blooms. 
This test does not say why nor imply why other people fail to have similar results.
It does not sat what causes algae either.

The only conclusion that can be made from the test is that we must reject the hypothesis that states excess nutrients = algae blooms in planted tanks. We then accept the alternative hypothesis, that something else is causing algae blooms other than excess nutrients.

Then we make a new hypothesis the test those alternatives and then go about testing them.
This is how we get somewhere in Science, little by little, step by step.
It is done with *many test,* sometimes we do get lucky, but that is very rare.

Hobbyists simply do not use standards and calibrated referenced methods for CO2, and very few measure light.
So how can you conclude much without doing that? Guess? You open yourself up to errors this way. 

No matter what else might be going on, if the aquarium has no algae and I know I am adding excess ferts at these levels, I know it cannot be due to excess ferts. This I can know nearly 100%, even if I'm not sure about my CO2.
If you have algae, well, then ......you have some confounding issue.

This method does not help convince those who have trouble with excess ferts and correlation  with algae.
But they have not confirmed their CO2/light either, so they are guessing without anything to back it up other than their own failings, lack of success. I think it is important to note, EI or excess ferts exposes weakness with light/CO2 balancing in the hobbyist horticultural skill set. If better management of light and CO2 are learned and mastered, then they can resolve the issue, this might takes a years for some, others seem to get it right off the bat. Still, limiting PO4 can reduce CO2 limitation and thus provide a method where the hobbyists could not fix the issue with CO2. But they still failed with CO2 and nutrients being independent, it does not change nor falsify the over all conclusion.

Regards, 
Tom Barr


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## ceg4048 (14 Jul 2010)

plantbrain said:
			
		

> ...For a control reference tank to be done, it must have no algae to start with.
> It also must have ample head room for non limiting CO2.


Tom, this is one of the most important factors limiting our ability to arrive at the 100% certainty. Few are able to run an algae free tank, either because of the things they believe or because of the things they do not believe. That's the first hurdle. Next hurdle is the ability to translate the beliefs into proper technique.

As you well know, few are willing to risk trashing their tanks in order to validate their beliefs or to perfect their techniques. There a thousand ways to be imperfect but only a few ways to be perfect. This inevitably results in tepid strength of belief and fosters lukewarm execution of technique.

The inability to de-couple nutrient loading from causality in our minds stifles expression of both belief and technique. I've tended to regard this therefore as more of a sociology issue, and less a scientific one. I've often found in helping others to troubleshoot algae issues that the suggested path is much less often "I'm 99% certain from tests I've done", than simply "C'mon, have some guts like Rambo, and Go For It!"

Cheers,


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## plantbrain (15 Jul 2010)

I can only demonstrate what something cannot be with any high degree of certainty, I can be so sure when I prove what something actually is caused by.

The test that falsified Paul and Kevin's hypothesis about PO4 15 years ago was valid then, it's not questioned at this point, as much as some might be tempted to. Some bite into this bait, this is a dead end however.
You can clearly show it cannot be true, no matter if they fail or not, that does not invalidate the test, it's just a case of poor methods in their experimental design. This is very different than adding real error/uncertainly to a test.

Such failures in the methods must be rejected as part of the test, since they add confounding error not due to chance, but due to experimenter methods error and are *systematic*. Statistics can measure/find confounding systematic error also in your experiment.


Regards, 
Tom Barr


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## plantbrain (15 Jul 2010)

ceg4048 said:
			
		

> plantbrain said:
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A picture of a successful, nicely planted tank seems to do well for convincing when I dose 15ppm NO3, 5ppm PO4, and .7ppm of Fe every other day with a full fish load after a few years of stability and a few thousand $ of plants and RCS sold. Beleive what you want, I'll laugh all the way to the bank.

How's them sociology apples?

I work a lot with farmers, and like to find good methods to kill aquatic weeds, so I know social skills both public and with country folks, and of course academic nit wits, and smart people. The web however.........brings out a different sociology of its own. Harder to help folks, more BS, rants, flame wars.......we've seen a few in the UK that involved lawyers etc, same deal here in the USA, over little old aquatic plants..........  

This stuff never would occur in person. You can see it in person, you can see everything, they can also help far more in person etc. There's an odd off element on line however.

Regards, 
Tom Barr


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## LondonDragon (16 Jul 2010)

Sometime last year I did an experiment with my tank, was running the 6x24w T5 over 125l, dosing 10X the recommended amount of EI, and pumping the CO2 to the limits the fish allowed. Run it like this for about 3 months, and did not see any increase in algae in comparison to when dosing lower quantities.


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## Mortis (21 Jul 2010)

You think maybe really healthy plants or true aquatic plants that are flourishing secrete something that prevents algae from having a party ?


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## ceg4048 (22 Jul 2010)

The prevailing thoughts are that if this were true then the application of aggressive water change schedule or the use of flow through system, which would remove these chemicals, or even the heavy application of activated carbon, which would sequester the chemicals would be correlated to poorer performance and a higher incidence of algae. The in-tank reality is exactly the opposite. Massive water removal (accompanied by the re-application of nutrients) and large quantities of activated carbon are strongly correlated to improved performance, not a decline in performance.

Although terrestrial plants are heavily engaged in chemical warfare to reduce predation by insects and other herbivores, there would seem to be little advantage for aquatic plants to use this strategy. For one, the massive water column would take a heavy toll on the concentration levels. Plants that are already nutrient and/or CO2 limited would be hard pressed to expend energy to continually generate toxic substances unless it happened to be a coincidence that their normal metabolic export products were toxic to nearby invaders. Again, what we see is just the opposite. Plant exported waste is usually toxic to the plants themselves and actually encourages algae. That's the prime reason for heavy water changes in the first place.

The answer may be a combination of things which include the possibility that the faster the leaf surfaces grow the less likely algae are able to attach to the surface. This may explain why slow growing plants like Anubias are so prone to some types of algae, despite being very healthy. Healthy plants also contribute to ammonia removal, whereas unhealthy plants slow their growth and export ammonia into the water column. Rapidly growing plants would also continually curtail the available lighting as well, whereas unhealthy plants would be less capable of doing so.. These factors likely combine to trigger germination of the algal seeds. Again, as Toms thread title suggests, this is more rationalization than something that we "know" right now.

Cheers,


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