Plants using bicarbonates for photosynthesis?

[Ullalaaqua]

Can’t keep this in anymore so here you go:
If you’ve read the journal about my nanotank you’ll know I got my rotalas to pearl without adding CO2. So I started to dig around after a friend of mine gave me some useful tips.


At this point I knew the reaktion behind those bubbles had something to do with bicarbonates (HCO − 3) and more spesifically the carbon (C) inside those carbonates.
Now I’m not a scientist and not really good understanding the complexity of waterchemistry and aquatic plant nutrition so I continued with a hunch here.

My hunch was that since I had no pressurized CO2 in the tank, no hardscape affecting the kh levels, the reaktion had to have something to do with the potassium (K) fertilizers - and watercare products that increase kh value.

So I made an experiment with ADA Brighty K which, if I have understood correctly, is potassiumcarbonate (K2CO3). After couple of hours I got bubbles again.

Today I tried the same with ARKA Microbelift Plants K that should be potassiumcarbonate too, but still no reaktion. So I read a bit more of
the study from Kaj Sand-Jensen (https://onlinelibrary.wiley.com/doi/abs/10.1111/fwb.12812). Turns out, the ph has to be 7 or more. Yesterday I added some tapwater (ph 8) to the tank to replase the evaporated water at the same time I dosed K...

So, if there is no bubbles when I get out of work, I’ll add some tapwater in it 😁

Would love to hear your thoughts about this! Especially from the ones who know a bit more about aquaticplants and waterchemistry. Am I even close with my hunch?

 

[Ullalaaqua]

I can’t edit this for some reason... But there was one photo missing from the first pearling earlier this week...
So here is a photo from that

 

[Zeus.]

Pearling can occur for few reasons
When the water is saturated with O2 and the water next to the leaves is unable to dissolve any more O2 bubbles form.
When water is saturated with gases esp after a Water Change (WC) these gases can form on plants, hardscape and tank.
After a WC esp in a non injected CO2 tank the extra CO2 in the tap water can give the plants a little edge with the extra CO2 and Photosynthesise a little faster and produce O2 a little faster, there are numerous reports of faster growth after WC which support the theory.
If plants are pearling soon after lights on and there hasn't been a WC I would be looking at the flow rate in the tank, as it would suggest to me that it might be inadequate.
If the light intensity is too high for the plants CO2 levels they will pearl, then get pin holes, then melt.

Although pearling can be great to see esp at first, it is a warning that you may be pushing the plants too hard with light intensity, so proceed with caution.

Although bicarbonates are used/added to tanks to increase the kH in tanks, which does enable folk to control the CO2 levels better/safer when injecting CO2 in tanks when users are using RO water. For most folk using tap water there is no need to add them, as there tap water supplies ample. Not sure what your water has in Finland - might be worth checking with your water supplier and you can normally find this online.

ADA Brighty K which, if I have understood correctly, is potassiumcarbonate (K2CO3).

Sorry you have been mis-informed. ADA do have some amazing products which are not cheap, but their fert line up is not one of them - ferts are ferts and plants do care which you use and ADA ferts are so over priced it is ridiculous IMO

 

[Ullalaaqua]

Pearling can occur for few reasons
When the water is saturated with O2 and the water next to the leaves is unable to dissolve any more O2 bubbles form.
When water is saturated with gases esp after a Water Change (WC) these gases can form on plants, hardscape and tank.
After a WC esp in a non injected CO2 tank the extra CO2 in the tap water can give the plants a little edge with the extra CO2 and Photosynthesise a little faster and produce O2 a little faster, there are numerous reports of faster growth after WC which support the theory.
If plants are pearling soon after lights on and there hasn't been a WC I would be looking at the flow rate in the tank, as it would suggest to me that it might be inadequate.
If the light intensity is too high for the plants CO2 levels they will pearl, then get pin holes, then melt.

Although pearling can be great to see esp at first, it is a warning that you may be pushing the plants too hard with light intensity, so proceed with caution.

Although bicarbonates are used/added to tanks to increase the kH in tanks, which does enable folk to control the CO2 levels better/safer when injecting CO2 in tanks when users are using RO water. For most folk using tap water there is no need to add them, as there tap water supplies ample. Not sure what your water has in Finland - might be worth checking with your water supplier and you can normally find this online.


View attachment 165810
Sorry you have been mis-informed. ADA do have some amazing products which are not cheap, but their fert line up is not one of them - ferts are ferts and plants do care which you use and ADA ferts are so over priced it is ridiculous IMO

Yes but I haven’t used this.... I used ADA Brighty K. Neutral does not affect kh values but the Brighty K does. And what comes for the other factors you listed, i’m aware of them, but none does seem to apply here. So this can’t be O2 related. Our tap water is really soft here. The kh and Gh are around 2-3. Ph in the other hand is 8.

 

[Ullalaaqua]

If plants are pearling soon after lights on and there hasn't been a WC I would be looking at the flow rate in the tank, as it would suggest to me that it might be inadequate.
If the light intensity is too high for the plants CO2 levels they will pearl, then get pin holes, then melt.

This is the other thing. I’ve seen those plants pearl 2 times now. First time the water change had been in the previous day and plants started to pearl couple of hours after lights went on. Yesterday about 2-3 hours too and I added more water to the tank.

 

[Zeus.]

but the Brighty K does

I stand corrected (followed the wrong link for the product ), however the same goes the the value of the product, making your own with some potassium carbonate would work out much cheaper.

Have you tried just adding the tap water to see if you get the same affect?

If there you pics of your plants they do look good and great colours

 

[John q]

Some fantastic looking rotala there.

Maybe I've got the wrong tank here but did these plants start off with added co2? If so then maybe they've built up a store of carbon and are using that up hence the pearling.

If these have indeed completely grown in low tech then I take my hat off to you.

Edit: just seen you haven't used co2 for 3 months.

 

[Ullalaaqua]

I stand corrected (followed the wrong link for the product ), however the same goes the the value of the product, making your own with some potassium carbonate would work out much cheaper.

Have you tried just adding the tap water to see if you get the same affect?

If there you pics of your plants they do look good and great colours

Yes the photos are from the tank in question 😄
Thanks.

I have added just water without dosing and this has never happened unless there was a waterchange just before. Now it didn’t happen with ARKAs K so just a hunch: The other is potassium bicarbonate and other potassiumcarbonate. Or I didn’t add water enough to rise ph to 7....

About ferts, I don’t see the point making my own mix since I don’t use EI method when dosing (my other tanks are with CO2). I’m more of a lean doser This nano is only 22l anyway, so I can experiment with it easily

I tested the tap water myself and I also get the parameters from the water supplier. They show the same reading normally. Only thing that differs sometimes is the kh from the tap water. Sometimes it’s 1 and other times 3. Don’t know if it matters much...

 

[Ullalaaqua]

Some fantastic looking rotala there.

Maybe I've got the wrong tank here but did these plants start off with added co2? If so then maybe they've built up a store of carbon and are using that up hence the pearling.

If these have indeed completely grown in low tech then I take my hat off to you.

Edit: just seen you haven't used co2 for 3 months.

Yes this tank had 2 weeks of CO2 injection in January and now we are at 3+ months without. So not really shure this could be the case. And if it was so, shouldn’t they be pearling in daily basis?

 

[jaypeecee]

Hi @Ullalaaqua

When people refer to plants 'pearling', they are referring to oxygen (O2) bubbles forming. But, I'm wondering if the bubbles you are seeing are carbon dioxide (CO2) bubbles instead. The addition of potassium carbonate and/or potassium bicarbonate to your tank water may be producing CO2, which is simply clinging to surfaces that are not smooth. I may be way off the mark and will give this some more thought.

JPC

 

[jaypeecee]

Hi @Ullalaaqua

There seems to be two sources of potassium (K) here:

Brighty Neutral K (derived from potassium chloride, KCl) and...
Brighty K which is 'strongly alkaline'. But, the label says nothing about its composition - unless I've missed something.

However, you do say:

So I made an experiment with ADA Brighty K which, if I have understood correctly, is potassiumcarbonate (K2CO3).

Where did you get the information that Brighty K contains potassium carbonate?

JPC

 

[John q]

Yes this tank had 2 weeks of CO2 injection in January and now we are at 3+ months without. So not really shure this could be the case. And if it was so, shouldn’t they be pearling in daily basis?

Apologies, I'd thought that co2 had only been stopped a few days ago.

 

[jaypeecee]

Hi @Ullalaaqua

Where did you get the information that Brighty K contains potassium carbonate?

I just checked the ADA website and, indeed, Brighty K is "derived from Potassium Carbonate". Here's a link:

https://www.adana.co.jp/en/contents/support/liquid/manuals/BRIGHTY_K_Label.pdf

JPC

 

[Andy Pierce]

If we take the label at its word, Brighty K is potassium oxide (K2O). K2O can be derived from potassium carbonate (K2CO3) by thermal decomposition but isn't the same as potassium carbonate. Adding K2O to water causes an immediate reaction (K2O + H2O → 2KOH) where the KOH dissociates into K+ (this is the potassium fertiliser component) and OH- which is the hydroxide anion, a very powerful base "strongly alkaline" (will raise pH) just as the label indicates. This is probably what Brighty K is... a solution of potassium hydroxide, whereas 'Neutral K' seems to be a solution of potassium chloride.

What happens to the hydroxide? You're injecting CO2 (and there is CO2 in the air) which will react with the hydroxide to form bicarbonate. Overall: KOH + CO2 →KHCO3. So you lose a little of your CO2, the pH you raised with the hydroxide comes back down (as the label states), and you increase the carbonate hardness (dKH) of your tank. More info on the reaction:

What are the products of KOH(s) + CO_2(g)? | Socratic

"KOH"_text((aq]) + "CO"_text(2(g]) -> "KHCO"_text(3(aq]) Potassium hydroxide, "KOH", will react with carbon dioxide, "CO"_2, to form potassium bicarbonate, "KHCO"_3, and water. The balanced chemical equation for this reaction looks like this "KOH"_text((aq]) + "CO"_text(2(g]) ->...

socratic.org

This leaves open the question of whether you actually want to increase the carbonate hardness of your tank while you're adding potassium...

 

[Zeus.]

If we take the label at its word, Brighty K is potassium oxide (K2O).

However the label says

'Derived from Potassium Carbonate' , its the Analysis that throw you as they use K2O - which is classic misdirection making it harder to clone the product, we worked out the ppm of K2O then worked out the corresponding ppm of K, once we had the K ppm and using K2CO3 we worked out ppm CO3 then the kH. Once we have the CO3 ppm or/and kH we have the clone

Big edit- made error in earlier post ( was watching TV and doing the mods to IFC )-
And the cost of making a clone with details

so same dose as ADA Brighty K

Interesting to see it adds approx 0.5kH a week at ADA dose
and the shocking price comparison
We had overlooked the fact ADA use K2CO3 when doing the ferts clones, so glad I found this out as that was a little oversight - in our defence we did have quite a bit to do. We have a new update due to the IFC Calculator and we might be able to get this on the next update @Hanuman

 

[jaypeecee]

Hi @Andy Pierce

So, what are the bubbles forming on the plants? Is it O2 or CO2?

TIA.

JPC

 

[Zeus.]

Made error in last post, which I spotted when checking maths- have updated post

 

[Andy Pierce]

Hi @Andy Pierce

So, what are the bubbles forming on the plants? Is it O2 or CO2?

TIA.

JPC

The classic test would be to collect the bubbles in a water-filled upside-down test tube, then add a glowing splint. If it bursts into flame it's O2; if it goes out it's CO2. If it explodes, it's H2.

 

[JoshP12]

Hi all,

My hunch was that since I had no pressurized CO2 in the tank, no hardscape affecting the kh levels, the reaktion had to have something to do with the potassium (K) fertilizers - and watercare products that increase kh value.

1) Role of Potassium in Carbon Dioxide Assimilation in Medicago sativa L ... it doesn't influence Rub, PSI, PSII ... so what does it influence?
2) Effects of potassium supply on limitations of photosynthesis by mesophyll diffusion conductance in Carya cathayensis Potassium (K) influences the photosynthesis process in a number of ways; however, the mechanisms underlying the photosynthetic response to differences in K supply are not well understood.

Those papers are for non-aquatic plants and have access to atmospheric CO2.

It gives us a starting point - Perhaps potassium is highly influential in photosynthesis, in particular, in the activation of enzymes/reaction channels required. No coincidence why it is the backbone to seachem and ADA system. In my mind, potassium is a driver of photosynthesis.

Rotala grows in low KH water and I would be pleasantly surprised if it has a mechanism (evolutionary adaptation) to utilize carbonates as say vals and/or cryts.

A question: How much of that growth has happened over the past 3 months? You can see some thinning on some older leaves but I do not know how old they are. Did they change into this state or just normal changing of growth?

There is a thought that "ideal" KH gives rise to "more efficient" CO2 acquisition so less does more. Perhaps because Rubisco doesn't work as well - no clue. Your tap water has low KH despite having higher pH ... so that "increase" will be temporarily.

Another piece to note is your surface agitation is low (from the photos I saw) and so any CO2 released from bacteria and/or respiration can be utilized ... if it doesn't get offgassed and the acquisition mechanism is more efficient, then a recipe for success! Your bacteria are your CO2 injection.

Notice: Staghorn after the observation of pearls? Pearls after potassium? The balance you had was perhaps shifted out by the addition of K ... throwing nutrient demand off balance ... allowing staghorn to take advantage?


Josh

 

[sparkyweasel]

There is a convention in ferilisers (and some other industrial chemicals) to express the amount of potassium in terms of how much K2O would give the same amount of potassium as is actually present although it may have come from other compounds, eg; K2CO3 or whatever.