Whats this then?

dw1305

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Hi all,
What I was trying to ask was this - at pH = 6.5, would a given plant absorb CO2 and HCO3- equally as this mix is roughly 50:50?
Not all plants can use HCO3-, so those ones will only be able to assimilate CO2 below pH7.
If not, what is the most efficient way of getting carbon into this plant?
There is an energetic penalty to using HCO3-, with plants that naturally grow in alkaline water they have to able to use HCO3-, because they never get DIC in any other form.
And, if Plant X cannot absorb carbon efficiently, is the simplest answer to replace it with a different plant that prefers pH less than 7.0 and soft water?
I think that most plants don't really care, some definitely grow best at low dKH, and others (like Vallisneria) don't do well in soft water (low dGH/dKH), but I don't know the exact mechanism.

cheers Darrel
 

jaypeecee

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Hi @dw1305

Many thanks, Darrel. I think it's slowly sinking in. I just dipped into Ecology of the Planted Aquarium and I note that Diana Walstad makes the statement that "About half of the aquatic plants that have been tested can use bicarbonates" and she references:

Madsen TV and Sand-Jensen K. 1991. Photosynthetic carbon assimilation in aquatic macrophytes. Aquat. Bot. 41: 5-40

Here is the Abstract:

https://www.sciencedirect.com/science/article/abs/pii/0304377091900376

The above reference rings a bell. Perhaps I mentioned it elsewhere.

JPC
 
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dw1305

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hypnogogia

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I think that most plants don't really care, some definitely grow best at low dKH, and others (like Vallisneria) don't do well in soft water (low dGH/dKH), but I don't know the exact mechanism.

cheers Darrel
Hmmm. I had to regularly remove Vallis from threat of taking over my tank, and I have a Gh of 7 and Kh of 4.5. I found Vallis grows best when you don’t do too many water changes.
 

X3NiTH

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I looked for a description for this and found that it’s a blue liquid so not Humic or Fulvic based and it apparently moderates pH significantly so as @Witcher states probably a blend of Citrates possibly Gluconates also.

If I was writing SciBlurb information for a product and it was Humic Acid based I’d probably be quoting the Cavin Cycle too because I’ll have used Citric Acid to moderate the pH down to a neutral number because Humic Acids are only soluble in Alkali conditions. Whatever the formula is it will be made with the cheapest and easiest to source ingredients.

Like Glut/Excel you’d have to be careful not to overdose this stuff not because it’s a biocide but due to pH moderation.

I haven’t seen any detrimental effects of overdosing beyond bottle instructions (within reasonable limits) to the Microbe-Lift Humic based carbon supplement. I would DIY it but it’s cheap enough and most easily available.

:)
 
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