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optimum carbon dioxide for elodea Canadensis?

jennnndawg

Seedling
Joined
23 Jun 2022
Messages
1
Location
kent
hello currently studying aquatic plants however I have not been able to find any suitable resource for the optimum concentration of carbon dioxide for elodea to perform photosynthesis - does anyone have a value for this? or a value for the optimum concentration of aquatic plants in general?
thank you :) (this is my first post please be nice!)
 

Matt1994

Member
Joined
12 May 2020
Messages
115
Location
North Yorkshire
Hi,
As far as I am aware its 30ppm
Which will show as a nice light green colour on your drop checker. The drop checker should be this colour when lights come on and stay this colour during the photoperiodic with no fluctuations. Many people do the 1ph drop. But personally I have only always used the
Drop checker (just taken time to assess and monitor the levels before entertaining Any live stock.
Hope this is of some help.

Sure someone else on here will be able to give an exact requirement or have a lot more knowledge Still relatively new myself !!

Thanks

Matt
 

dw1305

Expert
UKAPS Team
Joined
7 Apr 2008
Messages
13,988
Location
nr Bath
Hi all,
this is my first post please be nice!
Welcome to UKAPS.
..... or a value for the optimum concentration of aquatic plants in general?
currently studying aquatic plants however I have not been able to find any suitable resource for the optimum concentration of carbon dioxide for elodea to perform photosynthesis
There are lots of <"scientific references"> available via "Google Scholar", this one would be a good starting point (and should be open access?):

"Sand-Jensen, K., Riis, T., & Martinsen, K. T. (2022). <"Photosynthesis, growth, and distribution of plants in lowland streams—A synthesis and new data analyses of 40 years research">. Freshwater Biology, 67, 1255– 1271.

The simple answer is that all aquatic plants will grow more quickly at higher levels of CO2 (assuming that <"other nutrients aren't limiting">). The level of CO2 uptake will be dependent upon light availability ("photosynthetically active radiation").

For most non-obligate aquatic plants the optimal CO2 value will be <"above 420 ppm CO2"> (the present atmospheric level of CO2) and optimum growth of Tomato (Solanum lycopersicon) occurs <"at about 1000 ppm CO2">.

For obligate aquatic plants (plants that can't grow emersed and don't have any stomata) those values will be lower and you also have the added complication of the <"pH ~ carbonate ~ equilibrium">, meaning that much of the total inorganic carbon (TIC) may be in the form of bicarbonate (HCO3-) and Elodea spp. can utilise bicarbonate as their carbon source.

cheers Darrel
 

dw1305

Expert
UKAPS Team
Joined
7 Apr 2008
Messages
13,988
Location
nr Bath
Hi all,
"Sand-Jensen, K., Riis, T., & Martinsen, K. T. (2022). <"Photosynthesis, growth, and distribution of plants in lowland streams—A synthesis and new data analyses of 40 years research">. Freshwater Biology, 67, 1255– 1271.
I should have put the graphic and calculation for this:

............. Photosynthesis of different plant species belonging to four groups as a function of CO2 concentrations in the water. Th
photosynthetic rate.jpg
e terrestrial (secondary water) plant is Epilobium hirsutum. Amphibious plants are represented by Homophyllous amphibious, Berula ercta, and Heterophyllous amphibious (three blue lines), Callitriche cophocarpa, Sparganium emersum, and Sparganium erectum. Data for permanently submerged bicarbonate users (four red lines) are taken from studies of Elodea canadensis (HCO−3HCO3- 1 and 2 mM), Potamogeton crispus (HCO−3HCO3- 5.0 mM), Potamogeton pectinatus (HCO−3HCO3- 5.0 mM), and Ranunculus peltatus (HCO−3HCO3- 2.3 mM) Inset: photosynthesis <100 µM CO2. Photosynthetic rates are shown relative to maximum rates at high CO2 concentrations. Data from: Sand-Jensen (1983), Madsen and Sand-Jensen (1987), Madsen and Maberly (1991), and Sand-Jensen et al. (1992) .......

If we take 500 micromol. (as the point at which adding more CO2 doesn't increase plant growth) that can be converted to ppm CO2 using the RMM of CO2, which is equal to 44 (12 + (2*16)). A molar solution of CO2 is (a theoretical) 44g of gas dissolved in one litre of H2O.

Then just some shuffling about with the "powers of ten" (mg / L and ppm are equivalent) and multiplying by 500....... gives 500 micromol CO2 is equivalent to 22 ppm CO2. So it looks like @Matt1994 was pretty close.

cheers Darrel
 
Last edited:

sparkyweasel

Member
Joined
30 Jun 2011
Messages
2,482
(this is my first post please be nice!)
Welcome! :)
The 30ppm mentioned by @Matt1994 applies to aquariums with fish, shrimps, snails etc. It is generally considered a safe maximum for livestock.
In the absence of animals higher levels can give faster growth, - some people do this in a newly set-up tank to get the plants off to a good start and reduce the CO2 before introducing fish.
hth
 

sparkyweasel

Member
Joined
30 Jun 2011
Messages
2,482
Hi all, appologies to @jennnndawg i think i have misunderstud the information you where after,

thanks
matt
I hope you didn't think I was having a dig at you @Matt1994 , you are absolutely right for an aquarium forum. But it I thought it sounds like @jennnndawg is studying plants for their own sake, not in an aquarium context. I hope s/he will be back and perhaps tell us more. :)
 
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