Dissolved Oxygen meters

[rusticitas]

How useful, interesting and/or educational would a Dissolved Oxygen (DO) meter be toward learning and understanding planted tanks be? Or even for keeping killies, or anything else? This came up as I was reading a book on South American Dwarf Cichlids and every once in awhile there is a listing in a table for a specific species listing DO as milligrams per liter (mg/L) and that got me thinking about: (a) how is DO measured electronically; (b) what can it tell or indicate to us?

I still have some of my "economic stimulus" check left and came across the Milwaukee SM600 DO meter for ~$175 and was intrigued.

(I already have a PAR and pH/EC/TDS meter, and am experimenting with them.)

-Jason

 

[Tom Barr]

I have a DO meter new, but mnot 175$, 140$, new.
Same model.
Yes, they are useful for measuring the amount of plant growth/production.

Regards,
Tom Barr

 

[scottward]

Hey Tom, I understand that healthy photosynthesizing plants produce oxygen, and hence raise DO, but what about general DO levels for growth?

I understand that plants constantly respire, i.e. consume oxygen.

So, if DO levels are lousy to begin with, does this mean that plant growth will be severly restricted even if other variables such as light, nutrients, CO2 are excellent?

For some reason, Wikkipedia seems to be classing plants as anaerobic. So I'm thinking they fall into this category...

aerotolerant organisms, which cannot use oxygen for growth, but tolerate the presence of it

But given that plants respire all the time, and therefore, I assume, need oxygen, doesn't this mean that they are actually aerobic?




Scott.

 

[Biollante]

Not Tom And I May Have Misunderstood...


Hi Scott,

Could you provide a link and quote?

I haven’t done an extensive search but the only reference I find the the word aerobic in Wikipedia, “Plants,” is http://en.wikipedia.org/wiki/Plant is under “Ecology.”

Ecology

Main article: Plant ecology

The photosynthesis conducted by land plants and algae is the ultimate source of energy and organic material in nearly all ecosystems. Photosynthesis radically changed the composition of the early Earth's atmosphere, which as a result is now 21% oxygen. Animals and most other organisms are aerobic, relying on oxygen; those that do not are confined to relatively rare anaerobic environments. Plants are the primary producers in most terrestrial ecosystems and form the basis of the food web in those ecosystems. Many animals rely on plants for shelter as well as oxygen and food.

Land plants are key components of the water cycle and several other biogeochemical cycles. Some plants have coevolved with nitrogen fixing bacteria, making plants an important part of the nitrogen cycle. Plant roots play an essential role in soil development and prevention of soil erosion.

Though my understanding is limited, my understanding is that aerotolerant organisms are strictly fermentative. http://www.biology-online.org/dictionary/Aerotolerant.


The point of the Wikipedia quote above seems to be crediting plants for the environment the earth has now.


Sorry for butting in, if I misunderstood sorry again.


Biollante

 

[Biollante]

I Have Been Warned Against Butting In On "Guru Level" Discussions...


Hi Scott,


Your pull quote “aerotolerant organisms, which cannot use oxygen for growth, but tolerate the presence of it” seems to be from the Wikipedia article “Anaerobic Organism” http://en.wikipedia.org/wiki/Anaerobic_organism.


Under “Metabolism” it says the same as my above reference in post #4 above, “Aerotolerant organisms are strictly fermentative.”


Sorry for butting in, if I misunderstood.


Biollante

 

[scottward]

http://en.wikipedia.org/wiki/Oxygenation_(environmental)

Deoxygenation increases the relative population of anaerobic organisms such as plants and some bacteria, resulting in fish kills and other adverse events.

I think I got a bit lost Bio. Chances are I have taken something out of context here, and it's not actually a mistake at all. Dunno.

Please Bio, always butt in.

In another thread I have been discussing low DO impact on plants with Tom; Tom mentioned that the DO would have to be very low to have an impact on plants.

The more questions I ask the more I get confussed.

Scott.

 

[Biollante]

I Am Not A Wikipedia Fan


Hi Scott,


I don’t see your pull quote in that article, no big deal…


I certainly agree that low oxygen has a far greater adverse effect on our critters and our biological filtration than on plants in general.

Deoxygenation increases the relative population of anaerobic organisms such as plants

I disagree with the Wikipedia article “Oxygenation (environmental),” http://en.wikipedia.org/wiki/Oxygenation_(environmental) in the characterization of plants as anaerobic organisms even the link to the article “Anaerobic organism,” http://en.wikipedia.org/wiki/Anaerobic_organism does not mention plants as anaerobes. Plants are photosynthetic organisms that require some oxygen in the environment since they respire 24 hours a day and carry on photosynthesis only during daylight hours.



Biollante

 

[scottward]

Ah - I see what I have done.

Upon reading the 'Deoxygenation increased the relative population of anaerobic organisms such as plants', I have clicked the 'anaerobic organisms' hyperlink which took me to here, http://en.wikipedia.org/wiki/Anaerobic_organism, whereby I have then made the assumption that plants would then be 'aerotolerant organisms' as they didn't seem to fall into the other 2 categories presented.

Stupid wikipedia.

Stupid(er) me.

;-)

In the end though, it seems that I did pick up on something here that wasn't quite right. Unless the 'growth' part (i.e. 'cannot use oxygen for growth') has some significance?

But then again if plants aren't using the oxygen in some direct or indirect way towards growth, what exactly are they doing with it...?

I've often used Wikipedia as a reference for various things. Perhaps I shouldn't. ;-)

 

[Biollante]

Plants Are Oxygen Consumers As Well As Producers


Hi Scott,

Plants use oxygen for essentially the same reasons animals do. It is just that being photosynthetic, plants produce oxygen during daylight hours, but still require oxygen to survive at night. Also many of the organisms that help plants require oxygen as well.


Biollante

 

[scottward]

Cool. Thanks for the info Bio. I wonder how low you can go with O2 before plants do start to suffer - and I wonder what exactly happens? I guess the plants would probably start becoming mushy.

BTW - how much does a DO meter cost? Are cheap eBay ones ok, or are they rubbish?

Scott.