Dissolved Organic Compounds

[ElleDee]

I think when I said capacity you heard ability, which is not what I intended to convey.

Thanks for taking the time to write all that up. Yes, I misunderstood. I definitely have heard in the hobby that plants have no ways to deal with low oxygen environments, but I see that isn't what you said.

By comparison everything a plant needs to do to adapt is expensive and slow, because by definition plant structural changes compared to animal structural changes are expensive and slow. It's what it means to be a plant.

Plant macrostructures are fixed within their phenotypic parameters. They don't have reservoirs of erythrocyte precursors waiting in the wings. They can produce their immersed form. They have some range of structural variation, produce some more aerial roots etc. But subjected to progressive relative hypoxia in that environment, insufficient relative to the requirements that plant evolved to utilize, they cannot then construct more lacunal density to transport more oxygen.

They have no way to speed the oxygen transport process to starving tissues. Plants can only adapt to excessive hypoxia at the intracellular level: they re-engineer their mitochondria, they transition to alternate, less efficient ATP generation pathways and amino acid metabolic pathways, etc. Reengineering and transition processes that are energy expensive and slow.

Expensive and slow in a nutrient limited environment like underwater, equals stress.

I appreciate the article on various responses to hypoxia in plants vs other kingdoms. My animal knowledge is fairly limited, at least respective to plants, so it's difficult for me to compare them especially on something technical like energy requirements with animals. Way out of my wheelhouse! I do wonder about adaptations that are specific to aquatic plants rather than semi-aquatic. Specialist species often have unique structures and abilities to deal with unique challenges. I'm not about to do a lit search on it today or anything, just throwing it out there, and it doesn't change the fact that too little oxygen is a problem for flora and fauna and doing things that increase DO is good. Still not sure that's it's a problem in most tanks, but I'll kick in around in my mind for a while.

 

[Pepere]

I have found the discussion of dissolved organic carbon interesting.

My experience has been that increasing flow, water changes, tank cleanliness has greatly reduced algae issues.

Recently I have been visiting the Barr report and keyed in on an article entitled Non CO2 methods where Tom advocates for a low tech tank with no water changes no co2 light dosing of ferts etc.


So, how does this work with no water changes…? Why don’t you need to water change out DOC from the low tech tank to avoid algae?

Recently I started a 17 gallon fish bowl that uses a modified UGF and a box filter for mechanical filtration and easy flow kits on both for flow.

I have managed to keep the tank algae free without co2, albeit slow growth but also do weekly 50% water changes. The thought of achieving the same results without water changes is appealing, but also frightening.

I tried keeping a low tech tank without water changes before.. I mostly kept an Algae farm…

But the fact this is put out by Tom Barr has me thinking about it…

 

[ElleDee]

I have found the discussion of dissolved organic carbon interesting.

My experience has been that increasing flow, water changes, tank cleanliness has greatly reduced algae issues.

Recently I have been visiting the Barr report and keyed in on an article entitled Non CO2 methods where Tom advocates for a low tech tank with no water changes no co2 light dosing of ferts etc.


So, how does this work with no water changes…? Why don’t you need to water change out DOC from the low tech tank to avoid algae?

Recently I started a 17 gallon fish bowl that uses a modified UGF and a box filter for mechanical filtration and easy flow kits on both for flow.

I have managed to keep the tank algae free without co2, albeit slow growth but also do weekly 50% water changes. The thought of achieving the same results without water changes is appealing, but also frightening.

I tried keeping a low tech tank without water changes before.. I mostly kept an Algae farm…

But the fact this is put out by Tom Barr has me thinking about it…

I have never run CO2.

I think that you definitely can run low tech tanks with very little water changes, if you plan for it and get everything going smoothly. Yes, for sure. As for DOC levels in these kind of tanks, I think they are controlled by the limited inputs. Livestock is light and plant metabolism is slow, so DOC generation is low and can be decomposed at nearly the same rate.

But in the Tom Barr piece that I believe you are referring to he discourages large water changes on the grounds that your plants will get confused by the changing CO2 levels and will waste energy toggling between enzymes optimized for high- and low-CO2 availability environments. I am sure this has a scientific basis, but I've never found this to be true in practice. In my experience, big, regular water changes are always beneficial. Is this because the benefits of clean water outweigh the negatives he describes? Maybe. But I don't think it's accurate to assume that CO2 levels are stable in the first place. CO2 swings are prevalent in both natural systems and in my tanks due to bacterial respiration at night in the absence of photosynthesis, and that doesn't seem to confuse the plants. I just don't think that little nugget of advice from a long time ago has stood the test of time.

 

[Pepere]

think that you definitely can run low tech tanks with very little water changes, if you plan for it and get everything going smoothly. Yes, for sure. As for DOC levels in these kind of tanks, I think they are controlled by the limited inputs. Livestock is light and plant metabolism is slow, so DOC generation is low and can be decomposed at nearly the same rate.

Good info. My 17 gallon fish bowl is being run on air driven filtration and no co2 but is kind of heavily stocked. I will probably keep up with the water changes in it…

I am tempted though to attempt another 29 gallon tank with no CO2, easy plants scape, light fish stocking and try to find the balance that was so elusive before, and try to get by with minimal water changes just to see if I can pull it off…

The unrelenting algae is what pushed me in to CO2, and it gave a noticeable improvement early on…. Itwasnt the be all end all, but it was noticeable….

I started the 17 gallon bowl to see if I could keep a non co2 tank free of visible algae, but I have continued with weekly 50% waterchanges and filter servicing…

The idea of doing similar without weekly water changes intrigues me…

 

[Yugang]

But in the Tom Barr piece that I believe you are referring to he discourages large water changes on the grounds that your plants will get confused by the changing CO2 levels and will waste energy toggling between enzymes optimized for high- and low-CO2 availability environments. I am sure this has a scientific basis, but I've never found this to be true in practice.

I can speculate what @plantbrain meant, based on what I've read on Barreport.

Water from the tap may or may not contain a lot of CO2, depending on the source. Your source may have low CO2 @ElleDee, and no reason for concern. Certain sources however, like wells, may bring up to 50 ppm CO2, and if that would be added to a tank it may take a long time to get back to equilibrium with the original low tech conditions. So adding this weekly would not be insignificant and may add to the plant's confusion and cost of unnecessary adaptation.

Then apart from the confused plants continuously adjusting Rubisco, I read Tom's opinion (2013) that BBA will grow slowly in low tech, slow in proper high tech, but actually loves the range 5-10-15 ppm CO2 most. So, again speculating, Tom may have been concerned about algae growth as well by adding some, but not enough to be safe, CO2 to low tech.

 

[ElleDee]

Certain sources however, like wells, may bring up to 50 ppm CO2, and if that would be added to a tank it may take a long time to get back to equilibrium with the original low tech conditions.

Yeah, I can see where that might be a problem, and not just for this issue. How common is that I wonder? I would hope that people who have that kind of what be aware of that just from the post-WC ph swing alone.