Burr740
Planted Tanker
Im really glad you made this journal with detailed info about your methods. Good info like this just scatters in the wind on fb and social media
Journal sudiorca's non-CO2 supplemented softwater tanks
- Thread starter sudiorca
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BigWave
Active Member
You can literally see the growth rate. I bet if you measured the plants daily you could calculate it.
GreggZ
Moderator
I'm endlessly fascinated by this tank.
Plants are looking great. Hard to believe it's got no CO2.
Well done and keep the updates coming.
Plants are looking great. Hard to believe it's got no CO2.
Well done and keep the updates coming.
. I will definitely try to provide updates as frequently as possible.
sudiorca
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- #49
Thanks. I have been growing plants using this method for more than 4 years now. I believe that somewhat similar results could be possible without commercial active substrates. However, it does require a nutrient rich soil based substrate which can be capped with inert gravel or sand. I have this tank (shown below) which I setup more than 4 years ago with this method and it is still running quite well. It is not as colorful as my aquasoil based tanks, primarily because the plant species I am keeping here. I didn't use hetaer for more than 3 years in this tank (I was keeping shrimps here), I do have a heater for almost 6 months now for the betta, temp is about 78F and plants are doing okay so far. It is also possible to have a decent tank with inert gravel but not as vibrant as tanks with soil based substrates. I will highly recommend you to go through my previous comments especially #8 and #19 if you want to know the details of my setups.
5.5 gal tank with thin layer of organic potting mix capped with 1.5 inch+ fine gravel. Tank setup date - Oct 06, 2019. This is how the tank is looking right now.
sudiorca
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pH fluctuations in non-CO2 supplemented soft water (0-1 dKH) tanks:
It has been almost 5 months since I set up this little experimental jar. I added a base layer rich in organics and mixed it with old aquasoil to maintain porosity, this base layer was then capped with fresh aquasoil. The plants have been doing well throughout this entire time and it will be interesting to see how long it can sustain good plant growth. I have not added any fertilizer in the last couple of months. I briefly mentioned this setup during my talk at the AGA convention earlier this month.
I have been measuring pH of this jar at various time points for few days and I have found that there is roughly 0.5-unit pH swing every day. The last two images clearly show the pH rise from early morning to the peak photosynthesis period indicating consumption of CO2 by the plants. CO2 concentration increases at night primarily due to metabolic activities of microbes living in the substrate, along with plant and livestock respiration which decreases the pH of the water. Plants start to consume this accumulated CO2 when lights turn on which leads to the rise of pH and it takes few hours to reach an equilibrium (in this case it took somewhere between 3 - 4 hours) where uptake of CO2 is probably equal to the production of CO2 from biological activities and the pH doesn’t increase anymore throughout the rest of the photoperiod.
It has been almost 5 months since I set up this little experimental jar. I added a base layer rich in organics and mixed it with old aquasoil to maintain porosity, this base layer was then capped with fresh aquasoil. The plants have been doing well throughout this entire time and it will be interesting to see how long it can sustain good plant growth. I have not added any fertilizer in the last couple of months. I briefly mentioned this setup during my talk at the AGA convention earlier this month.
I have been measuring pH of this jar at various time points for few days and I have found that there is roughly 0.5-unit pH swing every day. The last two images clearly show the pH rise from early morning to the peak photosynthesis period indicating consumption of CO2 by the plants. CO2 concentration increases at night primarily due to metabolic activities of microbes living in the substrate, along with plant and livestock respiration which decreases the pH of the water. Plants start to consume this accumulated CO2 when lights turn on which leads to the rise of pH and it takes few hours to reach an equilibrium (in this case it took somewhere between 3 - 4 hours) where uptake of CO2 is probably equal to the production of CO2 from biological activities and the pH doesn’t increase anymore throughout the rest of the photoperiod.
This is a lot, but our normal conventions of stable CO2 (for the case of CO2 supplemented tanks) has nothing to do with what plants experience in their natural environment. In your jar this represents a CO2 ppm swing of a factor of three. That is 3 times more CO2 in early morning than at peak photosynthesis.
Are you assuming that CO2 exchange at the water surface is low compared to CO2 uptake and production?
A lot more can be said about what is going on when you measure the degassed pH of your water. How far will pH be below degassed in early morning (a good indicator of CO2 production) and how far above during peak photosynthesis (an indicator of the interplay between production, consumption and gas exchange).
A couple years ago I did numerical modelling of CO2, but I do understand that some would advise taking therapy sessions and just learn to enjoy growing plants. My focus was on CO2 supplemented, where injection is far higher than production and consumption, but it could also be very interesting for non CO2 supplemented.
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sudiorca
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Don't you think that should be the case based on roughly 10000 times slower diffusion of gases in water compared to air?
Please let me know if I am incorrect but based on my understanding, the atmospheric dissolution of CO2 yields less than 1 ppm CO2 in water at room temperature (it is about 0.5 ppm CO2). That's not good enough to support plant growth in my non-CO2 supplemented softwater tanks.
Microbial respiration, livestock respiration and respiration by plants (including root respiration) are the major sources of CO2 in these systems. Solubility of CO2 in water is quite high as we can seen below and as we have also witnessed with our pressurized CO2 injected tanks that it takes really long time to off gas the dissolved CO2 from water. Higher solubility of CO2 allows increased concentration of CO2 in water during night when there is no net uptake of CO2 by plants.
sudiorca
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- #55
@Yugang Here is another supporting information regarding the source of CO2 in these setups.
The temperature is hovering around 70-74F nowadays (perfect range for plants) in my place. The first picture shows 5.45 pH in the morning and the temperature reading is 73F.
However, the temperature dropped quite a bit few nights ago in my place as the heating was not working. I was intially surprised to see somewhat higher pH (second image, 5.62 pH) that morning even though the water temperature was about 10F (64F) lower than the other days. If the CO2 is actually coming from atmospheric gaseous dissolution then the pH should decrease with lowering temperature (higher solubility of gases) but I saw the opposite that morning. It took me a while to solve the mystery and it actually clearly indicates the origin of CO2 in these setups. Since CO2 is actually produced by biological activities inside the tank, lower temperature (64F is quite low) would decrease the metabolic rate of living organisms (less CO2 production) and that's why the pH was higher than other days. The temperature range from 70-75F maintains a nice balance between biological activities and solubility of gases in water.
The temperature is hovering around 70-74F nowadays (perfect range for plants) in my place. The first picture shows 5.45 pH in the morning and the temperature reading is 73F.
However, the temperature dropped quite a bit few nights ago in my place as the heating was not working. I was intially surprised to see somewhat higher pH (second image, 5.62 pH) that morning even though the water temperature was about 10F (64F) lower than the other days. If the CO2 is actually coming from atmospheric gaseous dissolution then the pH should decrease with lowering temperature (higher solubility of gases) but I saw the opposite that morning. It took me a while to solve the mystery and it actually clearly indicates the origin of CO2 in these setups. Since CO2 is actually produced by biological activities inside the tank, lower temperature (64F is quite low) would decrease the metabolic rate of living organisms (less CO2 production) and that's why the pH was higher than other days. The temperature range from 70-75F maintains a nice balance between biological activities and solubility of gases in water.
sudiorca
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- #56
@Yugang
I do have several other non-CO2 supplemented tanks where I do use hob filters and I do see pH fluctuations in those tanks.
Here is my 5.5 gal tank that I have been running for more than 4.5 years. I used a thin layer of organic potting mix as the base layer for this tank and capped it with inert fine gravel. I used tap water (3-4 dKH) for almost 3.5 years but I have been adding acid to decrease the KH (0-1 dKH) for almost a year now. Here is the pH reading in the morning.
Below is the pH reading after 5 hours since the lights turned on. I am using Aquaclear 20 hob filter for this 5.5 gal tank and it is rated for 100 gal/hr at max speed. I run it at minimum speed but I am only using couple of small coarse sponges in the filter. The flow/surface agitation is relatively strong for this tank as you can clearly see from this picture.
I do have several other non-CO2 supplemented tanks where I do use hob filters and I do see pH fluctuations in those tanks.
Here is my 5.5 gal tank that I have been running for more than 4.5 years. I used a thin layer of organic potting mix as the base layer for this tank and capped it with inert fine gravel. I used tap water (3-4 dKH) for almost 3.5 years but I have been adding acid to decrease the KH (0-1 dKH) for almost a year now. Here is the pH reading in the morning.
Below is the pH reading after 5 hours since the lights turned on. I am using Aquaclear 20 hob filter for this 5.5 gal tank and it is rated for 100 gal/hr at max speed. I run it at minimum speed but I am only using couple of small coarse sponges in the filter. The flow/surface agitation is relatively strong for this tank as you can clearly see from this picture.
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I now realise that your jar has no water circulation, and then indeed diffusion in the water could become a major obstacle and limit the exchange of CO2 with ambient air. I missed this, in my mind I always implicitly assume water circulation and a clear water surface.
I also found that, and it is confusing how we do not take this as the basis for calculations in our hobby. Indeed it means that our commonly used charts to calculate CO2 from pH are totally wrong.
Are you sure about this? Does this imply that all successful non CO2 injected tanks depend on..
So in other words, a non CO2 injected tank, or natural river/lake system, needs to be loaded with organics to keep the CO2 going and cannot depend on supply from atmosphere only?
Really fascinating experiments, and I have always been very impressed by your results @sudiorca
EDIT: I am clearly not knowledgeable about low tech tanks, mea culpa. Did some more research and see that indeed rivers in Amazon have CO2 ppm significantly above atmospheric. Also when reading low tech fora, now start seeing how important the decomposition in the soil is for CO2.
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Jhardee85
Active Member
This thread is the driving inspiration for my technically-not-allowed office project.
sudiorca
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- #59
It has been more than 6 months since I setup the 1.5 gal (approx) cylindrical jar. I am quite happy with the progress so far. Plants and shrimps are doing quite well. I am particularly impressed by the growth and size of Cryptocoryne parva 'mini'. I have this plant in two of my other non-CO2 tanks but their leaves are half the size compared to this jar. I monitored the pH change for one full week and the data looks quite fascinating for this jar, almost 0.9 unit of pH difference on certain days between the light cycle. The conditions are so drastically different in the mornings that most of the shrimps try to stay as close to surface as possible (as can be seen in the last photo, I did turn the light on to make the image). This behavior suggests that either the oxygen concentration is very low (quite logical, considering the large amount of plants, livestock and also microbial respiration during the dark period and the lack of water movement in this no-filter jar) or there is substantial increase in CO2 concentration (due to the same reasons) or both. The drop in pH after the lights turn off does indicate the possible increase of CO2 concentration (I do need to measure actual concentration of CO2 at some point).
Isn't it amazing how nature can take care of itself without us humans stabilising pH and CO2?
A lot to think about, including which assumptions we have in our mental models that are merely fabricated, not really reflecting what's going on with our plants. One of those classic assumptions is CO2 stability, which we usually track hourly within one day in the pH profile. But perhaps, if indeed stability is important and we do have a point here, it should be more on a moving average day-to day basis, or even longer periods, for the plant's Rubisco's machinery to stay well tuned and at minimum cost of adjustments? I am actually suspecting this is the case, but am no biologist and do not have data to prove or disprove the point.