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I have been thinking about setting up an experiment. Plants need co2, some more then others. For those that need more, we add it in various ways, pressurized, DIY, or glutaraldehyde (excel). The thing is, you won't find a pressurized co2 system in a natural waterway. When leaves, branches, or other things fall into the water they begin the process of decomposition. One of the byproducts of decomposition is co2. So it would stand to reason that if you had a tank with lots of decomposing matter such as leaf litter and a dirt substrate, that it would provide sufficient co2 for plants to use. I know this is kind of a walstad idea, but with walstad tanks people normally use the easy "begginer" plants, I would like to try this with plants that are considered high tech only. Has anyone done this before, or know of a thread that already discussed this?
 

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Plants in nature do not get the amount of Co2 and other nutrients that we supply in a planted tank. By providing these, I believe we "accelerate" the growth of plants to a degree that is greater than in a natural environment. I tried what you are suggesting, but the only plants that grew wild were Vallesneria. All other plants withered away or died due to algae growth. With high light most of the "high tech" plants grew well for a few weeks, but then algae growth smothered them. You really need to balance light, CO2 and nutrients, or make daily large water changes (think flowing water) and remove algae every day to keep a clean tank. Best of luck!!
 

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Interesting theory and worth giving it a try. What immediately comes to mind though is that most tanks with leaf litter are aiming to recreate a blackwater setup where its lots of roots and leaf litter but little to no plants.
 

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I'm pretty sure it was Tom Barr that suggested that the actual co2 concentrations in ponds and lakes is significantly higher than what would be expected from normal atmospheric dissolution. Not the 30ppm that you get in a high tech tank, but definitely more than .5ppm or so you get from diffusion. CO2 in Nature - Archivarium 2004 at the Age of Aquariums Not the original place I remember seeing it, but it'll get you started. That being said a lot of the natural processes that occur in lakes and ponds don't really occur in our tanks. This is due to a number of things, but mainly substrate depth and the lack of centuries of detritus build up that fuels decomposition and their assorted biological processes. The other thing that we can't really reproduce in our tanks without intervention is limitless fertilizers. While they may be at very low levels in nature from a ppm standpoint, they are effectively unlimited because of the volume of water. As such we should really add ferts to our tanks to compensate for this this, even in a low tech tank. I have 3 low tech tanks and from testing I have to dose nitrate every week in 2 of the 3 tanks as well as phosphate, iron and LARGE amounts of potassium weekly in all 3 tanks.

As to high tech plants in low tech tanks, I've had decent success with glosso, micro sword, ar and dwarf hairgrass in my dirted tanks. Not as lush as a high tech tank, but decent growth non the less. It is my belief that the dirt fosters some decomposition and bacterial processes that help increase co2 concentrations some.

If you're curious you can test (roughly) how much co2 is dissolved in your tank using the method outline here http://www.plantedtank.net/forums/11-fertilizers-water-parameters/28119-co2-measurements-dont-add-up.html#post241474 I used this test on my dirt tank here the hairgrass gros and after 12 hours lights out I had ~10 ppm co2, my sand tank here the hairgrass doesn't grow had almost no co2 disolved after the same time period.
 

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DIY... When leaves, branches, or other things fall into the water they begin the process of decomposition. One of the byproducts of decomposition is co2. So it would stand to reason that if you had a tank with lots of decomposing matter such as leaf litter and a dirt substrate,

Has anyone done this before, or know of a thread that already discussed this?
If you think about it, the process of yeast fermentation used in DIY is pretty close to your decomposition idea... transform complex sugars to CO2, but faster and cleaner for your tank.

The problem with decomposition is that it needs large amounts of O2 to prevent it from going anaerobic.... to add O2 to aquariums you will increase surface movement therefore reducing CO2 conc--- bottom line 0 gain. True, CO2 is a byproduct but so will be H2S and CH4... things that might make your aquarium not that fun to keep in the living room. Also you will have a good amount of debris all over the aquarium, including on plants.

From what I can remember from Walstad's book, she recommends that the substrate not be very rich in unprocessed organic matter precisely for the reasons above.

Bottom line, my position is that we should understand what happens in nature, but stop trying to reproduce it in our aquariums. Our aquariums lack the space and complexity of natural beautiful ecosystem. Furthermore, most of us do not want the huge monoculture patches, fine debris on leaves, seasonal changes, predation etc.

If you want to try it out, all the best and post it. Data on experiments is always nice to have, even if they fail.
 

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Discussion Starter · #7 ·
I'm pretty sure it was Tom Barr that suggested that the actual co2 concentrations in ponds and lakes is significantly higher than what would be expected from normal atmospheric dissolution. Not the 30ppm that you get in a high tech tank, but definitely more than .5ppm or so you get from diffusion. CO2 in Nature - Archivarium 2004 at the Age of Aquariums Not the original place I remember seeing it, but it'll get you started. That being said a lot of the natural processes that occur in lakes and ponds don't really occur in our tanks. This is due to a number of things, but mainly substrate depth and the lack of centuries of detritus build up that fuels decomposition and their assorted biological processes. The other thing that we can't really reproduce in our tanks without intervention is limitless fertilizers. While they may be at very low levels in nature from a ppm standpoint, they are effectively unlimited because of the volume of water. As such we should really add ferts to our tanks to compensate for this this, even in a low tech tank. I have 3 low tech tanks and from testing I have to dose nitrate every week in 2 of the 3 tanks as well as phosphate, iron and LARGE amounts of potassium weekly in all 3 tanks.

As to high tech plants in low tech tanks, I've had decent success with glosso, micro sword, ar and dwarf hairgrass in my dirted tanks. Not as lush as a high tech tank, but decent growth non the less. It is my belief that the dirt fosters some decomposition and bacterial processes that help increase co2 concentrations some.

If you're curious you can test (roughly) how much co2 is dissolved in your tank using the method outline here http://www.plantedtank.net/forums/11-fertilizers-water-parameters/28119-co2-measurements-dont-add-up.html#post241474 I used this test on my dirt tank here the hairgrass gros and after 12 hours lights out I had ~10 ppm co2, my sand tank here the hairgrass doesn't grow had almost no co2 disolved after the same time period.
Cool!! Thanks for those links, really helpful.
 
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