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Can CO2 micro bubbles cause incorrect drop checker readings?

xZaiox

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The biggest pH drop my livestock could handle was about 1.4pH and the DC was very light yellow to clear. I was also using CO2 reactors so there was no CO2 bubbles in tank
Zeus, can I ask what symptoms your livestock displayed when the CO2 was too high? I'm wanting to be extra vigilant and know what signs to look out for. I've read reports from people before who have claimed their only symptom was fish death, which is a worrying thought to me! I'm also confused how I was able to drop the pH 1.7 in the first place, from everything I have read, this sounds like in theory it should be a substantial overdose. As I was raising it, I kept thinking "surely they're going to head to the surface soon?".

Also thanks again to all those who have commented :thumbup:
 

Zeus.

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Zeus, can I ask what symptoms your livestock displayed when the CO2 was too high?
In my no fish 50l tank when the surface skimmer got blocked due to poor maintenance as forgot to clean it before going on holiday and scum was on the surface the high [CO2] caused the snails headed to the surface, plus lost some/most RCS in tank :eek:
In my 500l tank with a 1.4pH drop DC nearly clear some fish (Harlequin Rasbora )would be at the surface when lights first came on, then they would be fine unless I fed them, feeding them would get the fish to dart about for food (as they do) and the extra effort would cause the Harlequin Rasbora to pass out and go belly up for a short while, they recovered pretty quick. After that I would only feed the fish after CO2 had gone off and all was fine. Surface agitation was excellent in the 500l. I did get the 1.4pH drop in less than 30mins which may have caused some species of fish to go to the surface on pH drop for a short while whilst they adjusted.
Many of the fish I still have some 6 years plus on, tank no longer has CO2 injection as we have moved Olympus is calling
 

xZaiox

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In my no fish 50l tank when the surface skimmer got blocked due to poor maintenance as forgot to clean it before going on holiday and scum was on the surface the high [CO2] caused the snails headed to the surface, plus lost some/most RCS in tank :eek:
In my 500l tank with a 1.4pH drop DC nearly clear some fish (Harlequin Rasbora )would be at the surface when lights first came on, then they would be fine unless I fed them, feeding them would get the fish to dart about for food (as they do) and the extra effort would cause the Harlequin Rasbora to pass out and go belly up for a short while, they recovered pretty quick. After that I would only feed the fish after CO2 had gone off and all was fine. Surface agitation was excellent in the 500l. I did get the 1.4pH drop in less than 30mins which may have caused some species of fish to go to the surface on pH drop for a short while whilst they adjusted.
Many of the fish I still have some 6 years plus on, tank no longer has CO2 injection as we have moved Olympus is calling
This is useful info to me, cheers :thumbup:
 

Yugang

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What a pity. I hoped it would be higher.
Well, what's in a number if probably 80% of us (including myself), quoting a measured CO2 ppm number in tank water, may be as much as 20-50% off? **

It is pragmatic to prioritise day-to-day reproducible CO2, and stability over time during intra day photoperiod. Observe plants and lifestock, adjust slowly - whatever one believes ppm is.

** My personal estimation based on all assumptions, uncertainties and errors involved in the measurement and calculation process. If anyone thinks this is too pessimistic, please do consider sharing your experience and write an article on best practices for CO2 aquarium measurement, with evaluation of chemistry and physics involved and proposed measurement technique :lol:
 
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MichaelJ

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In my 500l tank with a 1.4pH drop DC nearly clear some fish (Harlequin Rasbora )would be at the surface when lights first came on, then they would be fine unless I fed them, feeding them would get the fish to dart about for food (as they do) and the extra effort would cause the Harlequin Rasbora to pass out and go belly up for a short while, they recovered pretty quick
Ouch that's terrible... I assume this was due to accidentally pumping in way too much CO2 with faulty equipments or incorrect adjustments or so... That would always keep me up at night if I would do CO2... I know it's a lot safer these days compared to how it used to be, but still.

Cheers,
Michael
 

John q

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Then there is the factor that any mist will collect on the under-side of leaves where stomata are abundant.
OK I need educating. Most scientific research suggests submerged aquatic plants don't have stomata, or if they do they aren't very efficient. Maybe I'm reading the "Wrong" research? Any help pointing me in the right direction would be appreciated 🙏
 

Simon Cole

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Most scientific research suggests submerged aquatic plants don't have stomata, or if they do they aren't very efficient. Maybe I'm reading the "Wrong" research? Any help pointing me in the right direction would be appreciated
Many true aquatic plants do not have stomata and use ectohydric surface capillary structures to obtain carbon dioxide through a process called laminar boundary layer conductance, which is a measure of diffusion. Some floating aquatic plants evolved non-functional permanently open stomata, and some simply exhibit a "loss of function" that could still allow them to adapt and close during periods of environmental stress. Pteridophytes which include ferns like Bolbitis, mosses, and certain liverworts, evolved a kidney-shaped (reniform) graminoid stomata, many of which stay open and retain the ability to close in dryer conditions. Marchantialean liverworts like Riccardia evolved without them, using special pores for photosynthetic gas exchange on the under sides of their leaves, and with humid air chambers beneath the cuticle. The role of air chambers is to enable endohydrotic conductance and this is thought to enhanced gaseous exchange and strike a balance between hydroscopic (wet) and hygroscopic (damp) environmental conditions (Vascular Transport in Plants, pages 69-89); there are also suggestions that some plants form similar air spaces (aerenchyma) as an adaptation to when they have been flooded. Generally speaking, plants that did evolve stomata, did so on the under side of leaves (hypostomatous), on both sides (amphistomatous), or on the top (epistomatous) to favour their own ecological niche.

However, plants that evolved "true" stomata, probably did so in more hydrodynamic conditions, and they make up the bulk of "immersed" aquarium stem plants that people are usually interested in enriching. When we see "pearling" we are probably observing very fast degassing, and it is likely that plants have opened their stomata to facilitate a rapid gaseous exchange. Flooding-induced stomatal closure is common in many terrestrial plants but nobody really knows how this happens. If certain immersed aquarium plants respond in the same way, then the question is, do they open back up again. And another question on my mind is, when they are closed, how big is the actual gap, and does this facilitate access of carbon dioxide bubbles into the intercellular spaces behind the guard cells; nano-bubbles are < 200 nm, so they only need a small gap to enter. For each plant species it is going to be slightly different and will depend upon varying environmental factors, but there have been suggestions that stomata in most species will open back up again when the osmotic conditions are suitable. It would be great if we knew the mechanism or if immersed aquarium species were studied independently, but for the time being this is simply a guess.

It is probably untrue to assume that stomata reduce in prevalence on immersed aquarium plants as an adaptation. They may close and be less recurrent in new growth, but there is not conclusive evidence that they disappear. Arabidopsis (stomatal initiation) is the process that governs whether the leaf meristemoid mother cell differentiates into either a pavement cell (standard epidermal) or a stomatal guard cell. It governs the stomatal abundance of a leaf (e.g. the stomatal index), and this is confined by the “one cell spacing” rule, and many other factors such as light intensity, gaseous exchange and temperature play an important role in stomatal abundance. We know that many C3 plants will often increase stomatal abundance when there are lower carbon dioxide levels and this seems to be a long-term evolutionary trait, but there is also species specific variation. Whether this process is affected by immersed growing conditions is also likely to be species specific.

If stomata are open, then both hypostomatous and amphistomatous leaves will have a potential for capturing carbon dioxide bubbles of all sizes as well as dissolved carbon dioxide. That would imply that pH measurement and ppm approximations might not really be the target of investigation. Instead, "pearling" may be a far more accurate way to measure photosynthesis, not least because it is a measure of the effect of enrichment, as others have pointed out above. Plants that do this are good indicators that conditions are right. Plus it is best not to eliminate the role of aqueous pores and other gateways that probably provide a route for carbon dioxide bubbles to enter directly. After all, carbon dioxide diffusivity is about 10,000 times higher in air than in water, so if it is present in bubbles inside plant tissue (intercellular gaps) or sitting as a bubble in the stomatal opening, then the rate of diffusion into chloroplasts will be far faster. The rate of diffusion of an ionic solute or carbon dioxide molecules is inverse to the distance. It is a bit like standing next to the speaker in a punk rock concert, compared to hearing the faint rumble of a rave going on several miles away!
 
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bazz

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Many true aquatic plants do not have stomata and use ectohydric (surface capillary structures) to obtain carbon dioxide through a process called laminar boundary layer conductance, which is a measure of diffusion. Some floating aquatic plants evolved non-functional permanently open stomata, and some simply exhibit a "loss of function" that could still allow them to adapt and close during periods of environmental stress. Pteridophytes which include ferns like Bolbitis, mosses, and certain liverworts, evolved a kidney-shaped (reniform) graminoid stomata, many of which stay open and retain the ability to close in dryer conditions. Marchantialean liverworts like Riccardia evolved without them, using special pores for photosynthetic gas exchange on the under sides of their leaves, and with humid air chambers beneath the cuticle. The role of air chambers is to enable endohydrotic conductance and this is thought to enhanced gaseous exchange and strike a balance between hydroscopic (wet) and hygrophytic (damp) environmental conditions (Vascular Transport in Plants, pages 69-89); there are also suggestions that some plants form similar air spaces (aerenchyma) as an adaptation to when they have been flooded. Generally speaking, plants that did evolve stomata, did so on the under side of leaves (hypostomatous), on both sides (amphistomatous), or on the top (epistomatous) to favour their own ecological niche.

However, plants that evolved "true" stomata, probably did so in more hydrodynamic conditions, and they make up the bulk of "immersed" aquarium stem plants that people are usually interested in enriching. When we see "pearling" we are probably observing very fast degassing, and it is likely that plants have opened their stomata to facilitate a rapid gaseous exchange. Flooding-induced stomatal closure is common in many terrestrial plants but nobody really knows how this happens. If certain immersed aquarium plants respond in the same way, then the question is, do they open back up again. And another question on my mind is, when they are closed, how big is the actual gap, and does this facilitate access of carbon dioxide bubbles into the intercellular spaces behind the guard cells; nano-bubbles are < 200 nm, so they only need a small gap to enter. For each plant species it is going to be slightly different and will depend upon varying environmental factors, but there have been suggestions that stomata in most species will open back up again when the osmotic conditions are suitable. It would be great if we knew the mechanism or if immersed aquarium species were studied independently, but for the time being this is simply a guess.

It is probably untrue to assume that stomata reduce in prevalence on immersed aquarium plants as an adaptation. They may close and be less recurrent in new growth, but there is not conclusive evidence that they disappear. Arabidopsis (stomatal initiation) is the process that governs whether the leaf meristemoid mother cell differentiates into either a pavement cell (standard epidermal) or a stomatal guard cell. It governs the stomatal abundance of a leaf (e.g. the stomatal index), and this is confined by the “one cell spacing” rule, and many other factors such as light intensity, gaseous exchange and temperature play an important role in stomatal abundance. We know that many C3 plants will often increase stomatal abundance when there are lower carbon dioxide levels and this seems to be a long-term evolutionary trait, but there is also species specific variation. Whether this process is affected by immersed growing conditions is also likely to be species specific.

If stomata are open, then both hypostomatous and amphistomatous leaves will have a potential for capturing carbon dioxide bubbles of all sizes as well as dissolved carbon dioxide. That would imply that pH measurement and ppm approximations might not really be the target of investigation. Instead, "pearling" may be a far more accurate way to measure photosynthesis, not least because it is a measure of the effect of enrichment, as others have pointed out above. Plants that do this are good indicators that conditions are right. Plus it is best not to eliminate the role of aqueous pores and other gateways that probably provide a route for carbon dioxide bubbles to enter directly. After all, carbon dioxide diffusivity is about 10,000 times higher in air than in water, so if it is present in bubbles inside plant tissue (intercellular gaps) or sitting as a bubble in the stomatal opening, then the rate of diffusion into chloroplasts will be far faster. The rate of diffusion of an ionic solute or carbon dioxide molecules is inverse to the distance. It is a bit like standing next to the speaker in a punk rock concert, compared to hearing the faint rumble of a rave going on several miles away!
I'm glad you're on UKAPS!
 

dw1305

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Hi all,
Most scientific research suggests submerged aquatic plants don't have stomata, or if they do they aren't very efficient.
What @Simon Cole says. Evolution, via <"natural selection">, is <"pretty efficient"> at finding the <"optimal solution"> ("optimal" depends a little bit <"where you start from">).

From <"What's the general consensus on a back up heater?">.
This is a cross-section through <"the floating leaf of a Potamogeton sp"> (it is floating because you can see that there are stomata only in the upper (adaxial) leaf surface).
36716447811_82c0590310_c-jpg.176440


cheers Darrel
 

Simon Cole

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Buckingham
Other thoughts on incorrect drop checker readings:
Bubbles adhere very quickly to glass. Depending upon the type of drop checker you choose, this can have an impact on measurement. As more bubbles combine against the glass surface, their buoyancy overcomes surface tension and they float upwards into the drop checker. This provides a sort of motorway express lane from aquarium water into the drop checker. Drop checkers can be categorised as having wide or narrow openings. In an ideal world, the gas pocket would be as small as possible, there would be minimal opportunity for bubbles to collect, adhere, and move up the glass into this airspace, and the interface between aquarium water and the gas pocket would be maximised. I have used both types and feel that they are both useful, but I am guessing that the narrow ones are better. Let me explain why:
1651873494365.png
< note how this "wide" drop checker has potential to capture more carbon dioxide bubbles through glass-adhesion mechanism because more aquarium water is in contact with the glass inside the cone, and also how the wide opening functions to captures bubbles.
1651873949268.png
< this "narrow" drop checker is a bit more ideal. The meniscus is convex and will deflect bubbles away from the opening. Minimal bubbles can adhere to the glass and travel inside. There is lots of indicator fluid, and a smaller gas pocket than if the opening was widened. Had this been suctioned onto the glass nearer to the plants, then it would be comparatively more effective, but assuming that flow-dispersion is not a major factor, then it is hard to fault.

Bubbles can flatten. Silanized glass is hydrophobic, and bubbles can flatten against it when they adhere (shown below), and this process takes a matter of milliseconds depending upon the concentration of solutes, molecules that coat them, and a few other factors; the appearance is often a glimmering sheen. If drop checkers use regular glass, I suspect that any adhering bubbles are more rounded but still have strong adhesive forces, a tendency to combine, and buoyancy sending then upwards. I do not have strong opinions favouring either glass type. Here is a milli-bubble adhering to silanized glass over 2 milliseconds:
1651850657208.png

As a side note, I think that the bubble flattening effect is more important if it happens on plant leaves. The morphology of plant leaves varies a lot from species to species, but they are not perfectly flat surfaces. I couldn't find any SEM images of aquarium plants to show you. I would presume that bubbles contacting leaves may either adhere to, get trapped, flatten, or provide a sheen over the leaf epidermis. This indicates that the size of bubbles is possibly very important, especially without open stomata, but apologies this is very off topic.
 

Yugang

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Messages
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Location
Hong Kong
Other thoughts on incorrect drop checker readings:
Bubbles adhere very quickly to glass. Depending upon the type of drop checker you choose, this can have an impact on measurement. As more bubbles combine against the glass surface, their buoyancy overcomes surface tension and they float upwards into the drop checker. This provides a sort of motorway express lane from aquarium water into the drop checker. Drop checkers can be categorised as having wide or narrow openings. In an ideal world, the gas pocket would be as small as possible, there would be minimal opportunity for bubbles to collect, adhere, and move up the glass into this airspace, and the interface between aquarium water and the gas pocket would be maximised. I have used both types and feel that they are both useful, but I am guessing that the narrow ones are better. Let me explain why:
View attachment 188094< note how this "wide" drop checker has potential to capture more carbon dioxide bubbles through glass-adhesion mechanism because more aquarium water is in contact with the glass inside the cone, and also how the wide opening functions to captures bubbles.
View attachment 188095 < this "narrow" drop checker is a bit more ideal. The meniscus is convex and will deflect bubbles away from the opening. Minimal bubbles can adhere to the glass and travel inside. There is lots of indicator fluid, and a smaller gas pocket than if the opening was widened. Had this been suctioned onto the glass nearer to the plants, then it would be comparatively more effective, but assuming that flow-dispersion is not a major factor, then it is hard to fault.

Bubbles can flatten. Silanized glass is hydrophobic, and bubbles can flatten against it when they adhere (shown below), and this process takes a matter of milliseconds depending upon the concentration of solutes, molecules that coat them, and a few other factors; the appearance is often a glimmering sheen. If drop checkers use regular glass, I suspect that any adhering bubbles are more rounded but still have strong adhesive forces, a tendency to combine, and buoyancy sending then upwards. I do not have strong opinions favouring either glass type. Here is a milli-bubble adhering to silanized glass over 2 milliseconds:
View attachment 188072
As a side note, I think that the bubble flattening effect is more important if it happens on plant leaves. The morphology of plant leaves varies a lot from species to species, but they are not perfectly flat surfaces. I couldn't find any SEM images of aquarium plants to show you. I would presume that bubbles contacting leaves may either adhere to, get trapped, flatten, or provide a sheen over the leaf epidermis. This indicates that the size of bubbles is possibly very important, especially without open stomata, but apologies this is very off topic.

I find it hard to quantify, and you may be right with your preference for the narrow dropchecker.

We could also make a case for a 'wide' drop checker, as it has a larger surface area between aquarium water and the pocket of gas, allowing a faster gas exchange and perhaps sooner equilibrium in the checker fluid.

A too narrow (approaching zero) checker certainly won't work, as there is no gas exchange at all. Perhaps there is somewhere an optimum between 'narow' and 'wide'.

I used both types simultaneously, and eventhough I was not interested in a full investigation I believe my results showed indeed a faster response of the 'wide' type.

While a drop checker can be easily understood for a static situation with fully dissolved CO2 in aquarium water, it is far less obvious when changes over time happen, or when CO2 bubbles of various sizes are present (visible bubbles / mist).
I have not done the math, but quantitatively understanding the workings in a non-static / not-fully-dissolved situation can become very tricky indeed as there are multiple processes of diffusion/outgassing /absorption/flow going on. For same reason it is hard to argue what is the best design. Just test one against the other is probably the best approach.
 

Zeus.

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Ouch that's terrible... I assume this was due to accidentally pumping in way too much CO2 with faulty equipments or incorrect adjustments or so... That would always keep me up at night if I would do CO2... I know it's a lot safer these days compared to how it used to be, but still.

Cheers,
Michael
No accident or faulty equipment, Due to some CO2/flow related issues which I was trying to resolve by improving the CO2 supply to the plants, by going down the high[CO2] route which I would advise against with hindsight. When I took [CO2] too high initially the fish was at the surface just after the pH drop, so a backed off a little and all was fine. However, if I fed the fish the Harlequin Rasbora/myself wasn’t happy with a :eek: moment!!! they very quickly recovered :angelic:, I didn’t feed them again till CO2 had gone off and it didn’t happen again. So it was the Harlequin Rasbora when being fed was the visual waring in tank that [CO2] was too high. Only had tank that high for a short while and never took the [CO2] any higher and never lost a fish in 500L tank due to high [CO2]. Once I got my Maxspect Gyres x2 and improved the tank flow/turnover I dialled back on the [CO2], which is the route I would advise if your [CO2] with 1.0pH drop isn’t doing what you had hoped, Increasing the tank turnover/flow helps remove/reduce the ‘dead spots’ and increase the supply of CO2 to your plants. Maxspect Gyres are great for the planted tank IMO/IME as you can have a timed schedule with different flow rates for each Gyre, high when CO2 is on variable speeds and low/off at night so clean up crew can do their job. In the words of our 'CO2 Guru' Clive ‘Flow is King in the CO2 enriched planted tank’ and many CO2 related issues are flow related issues

Only ever lost RCS in 50l (no fish in tank) due to forgetting to cleaning Ehiem skim before holiday 😢 it got clogged with detritus stopped skimming and returned home to the surface full of scrum.
 
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