Nutrients and Algae - A Small Experiment

aquabillpers

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To learn more about this, on September 12 I filled two, two gallon jars with moderately hard, alkaline well water. To one was added enough KNO3 and Fleet Enema to raise nitrates and phosphates to about 60 (actually, probably 50 - 100) and 1.5, respectively. The other, undosed, tested at 7 and .1. Each was inoculated with a small amount of hair algae and placed in a location where it got 8 to 10 hours a day of direct sunlight.

The hair algae in the undosed tank died on the third day, turning white. More was added and it met the same fate.

By September 29 the jar that was dosed had a fairly strong coating of hard green algae (GSA?) on the glass. The undosed jar had very little algae. Neither had green water.

From this I conclude that excessive nitrates can cause algae and, conversely, if the excess is reduced, the amount of algae will also diminish.

During the course of the experiment, about half of the water evaporated. The dosed jar shows a ring of (apparently) calcium carbonate; the undosed jar shows no such ring. I wonder why?

In the picture below, the jar on the left is the undosed one.

Bill
 

Tom Barr

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Re: Nutrients and Algae - A Small Experiment

So what do you conclude?

Something will grow there, you have a choice of what that is.
Also, the amount of light you added is insane relative to our tanks(50-200 micro moles vs 1500-2000).

Regards,
Tom Barr
 

aquabillpers

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Re: Nutrients and Algae - A Small Experiment

All that I conclude is that a lot of nitrates seem to cause algae.

Both jars got the same "insane" amount of light. The only variables were the amounts of nitrate and phosphate.

Bill
 

brwaldbaum

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Re: Nutrients and Algae - A Small Experiment

I'm not sure why you conclude that excessive nitrates cause algae when the dosed jar also had 15x the amount of PO4 relative to the non-dosed jar. Also, I think the more relevant question would have been, "Does excessive NO3/PO4 cause algae in the presence of plants?". In other words, you should have tossed some hornwort in each jar.

Nevertheless, it was an interesting experiment.

Brian
 

Laith

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Re: Nutrients and Algae - A Small Experiment

Yes, interesting. Would be more relevant to do the same experiment with a dense plant mass.

There is a reason that one of the most important factors of success is to start with enough plants. Most people do not.
 

Tom Barr

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Re: Nutrients and Algae - A Small Experiment

aquabillpers said:
All that I conclude is that a lot of nitrates seem to cause algae.

And this surprises you? I would say the same thing as well given the set up.

Both jars got the same "insane" amount of light. The only variables were the amounts of nitrate and phosphate.
Bill

I'm not talking about the each replicate, but relative to what other factor? Plants..........algae do better at higher light levels, plants are more effective light competitors and this is their main "competing" method with respect to algae.

Reduce the light down to 1.5 to 2w gal and try this same thing.

Next pack one with lots of weeds, the other leave empty.

Regards,
Tom Barr
 

aquabillpers

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Re: Nutrients and Algae - A Small Experiment

Thanks for your comments.

My point in this was to prove or disprove the contention that "Excess nutrients do not cause algae." The results speak for themselves, I think.

I'm sure that there was no ammonia present, either.

Sure, the environment was extreme, but that is one of the ways that you test a hypothesis - exaggerate the variable that you want to test. Right, Tom?

I'm off to watch the Red Sox beat the Yankees.

Bill
 

Laith

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Re: Nutrients and Algae - A Small Experiment

aquabillpers said:
...
My point in this was to prove or disprove the contention that "Excess nutrients do not cause algae." ...

I have always understood that the rest of the phrase is "... in a planted tank". Am I missing something here? I don't remember anyone ever saying that in a container of water with no plants, excess nutrients do not cause algae. Why would anyone say that? We are into *planted* tanks.

I would be interested to see this experiment done more in line with the subject matter: planted tanks...
 

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Re: Nutrients and Algae - A Small Experiment

aquabillpers said:
Thanks for your comments.

My point in this was to prove or disprove the contention that "Excess nutrients do not cause algae." The results speak for themselves, I think.

Yes, if isolate the algae alone.
I would predict this also and could prove it also.

I'm sure that there was no ammonia present, either.

Sure, the environment was extreme, but that is one of the ways that you test a hypothesis - exaggerate the variable that you want to test. Right, Tom? I'm off to watch the Red Sox beat the Yankees.

Bill

I wish the Red Sox well, they needed to win and still do:)

But about the test, without plants, algae will grow. So excess nutrients, NO3 etc will cuase some algae bloom, but with plant present the algae will not grow.

So will the jars grow the same algae with NH4?
You can try that next.

Then try it with and w/o weeds, repeat the same test, once with NO3 and the next with NH4.

There are some other factors you are also not considering such as substrate, water movement as well if you try to apply this to our tanks etc.

Regards,
Tom Barr