Wouldn't that have to do with how much oxygen is in the water in the first place? A warm tank with no oxygen in it won't pearl, but a cold tank that's already saturated will pearl...it also has to do something with water movement and surface agitation. But I would assume yes, colder water would be harder to pearl plants in. However, the rule about saturation also applies to carbon dioxide, which plants need for photosynthesis and oxygen production as well....
Pearling and Temperature
Pearling occurs when oxygen produced by plants cannot dissolve into the water column because the tank is already completely saturated with oxygen.
Warm water cannot hold as much dissolved oxygen as cold water, so presumably it has a lower saturation point.
Does this mean that pearling is less likely to be observed in a cold water tank?
Warm water cannot hold as much dissolved oxygen as cold water, so presumably it has a lower saturation point.
Does this mean that pearling is less likely to be observed in a cold water tank?
1 - 16 of 16 Posts
Was just thinking about this the other day...
I would think it's more of a wash because the cooler water also holds more CO2 (provided you're injecting), thus driving the process and the efficiency of it further.
I would think it's more of a wash because the cooler water also holds more CO2 (provided you're injecting), thus driving the process and the efficiency of it further.
So I know that cooler water has a higher capacity for CO2, but does that mean it will typically have a higher concentration? If I have a 16 wheeler and you have a pickup truck, clearly my 16 wheeler has the capacity to hold more boxes in it, but that doesn't guarantee anything: you could have 8 boxes in your pickup and my 16 wheeler could be empty.
Does cold water off gas CO2 more slowly, or does it just have the ability to store more CO2?
Does cold water off gas CO2 more slowly, or does it just have the ability to store more CO2?
Total speculation on my part... but a warm carbonated beverage vs a cold carbonated beverage (both open to the atmosphere) behave differently as far as retaining CO2. Carbon dioxide is less soluble in warmer liquids.
I guess I'm just thinking of it from a standpoint of "I can hold more CO2 in cooler water, and therefore would have increased retention of the current dosage of what I'm injecting". Either that, or I would/could have better efficiency of what I'm injecting presently (assuming I don't already have 100% dissolution already).
I guess in a situation where you inject X quantity of CO2 and aren't at the max of what the solution can potentially hold, then drop the temp a few degrees (increasing the room to hold more O2), it would take longer to pearl. That's my best guess.
I guess I'm just thinking of it from a standpoint of "I can hold more CO2 in cooler water, and therefore would have increased retention of the current dosage of what I'm injecting". Either that, or I would/could have better efficiency of what I'm injecting presently (assuming I don't already have 100% dissolution already).
I guess in a situation where you inject X quantity of CO2 and aren't at the max of what the solution can potentially hold, then drop the temp a few degrees (increasing the room to hold more O2), it would take longer to pearl. That's my best guess.
The off gassing is more of a surface area/water circulation thing than a warm vs cold. If you have two containers with the same surface area open to atmospheric gas (i.e. air), and one is warmer than the other, then the warmer one will contain less CO2 and O2 than the other container.
Off gassing = surface area/water circulation
Capacity = temperature of water
concentration = weird combination of off gassing and capacity
Off gassing = surface area/water circulation
Capacity = temperature of water
concentration = weird combination of off gassing and capacity
If you take the same system with the same parameters (including CO2 conc. ) and warm it up you will notice more pearling forming. As you rightly point out this is because water can hold less gas at higher temperatures. However a significant confounder to quantifying this increase is that plants' metabolism will also speed up or slow down with temperature.
The effect of temperature on actual ppm CO2 at a specific pH is somewhat small and easily covered by the margin of error given by our measuring equipment. Temperature does lower the saturation point but we are unlikely to reach CO2 saturation in our aquariums.. it is something like at 20°C you have a saturation point of 1700ppm, at 30°C of only ~1300ppm
The effect of temperature on actual ppm CO2 at a specific pH is somewhat small and easily covered by the margin of error given by our measuring equipment. Temperature does lower the saturation point but we are unlikely to reach CO2 saturation in our aquariums.. it is something like at 20°C you have a saturation point of 1700ppm, at 30°C of only ~1300ppm
This is what I figured. So in that case, I'm assuming that temperature does not factor into CO2 levels because our tank are never fully saturated with CO2 anyway, so the capacity is never reached. A saturated aquarium would basically be full of seltzer.The off gassing is more of a surface area/water circulation thing than a warm vs cold. If you have two containers with the same surface area open to atmospheric gas (i.e. air), and one is warmer than the other, then the warmer one will contain less CO2 and O2 than the other container.
Off gassing = surface area/water circulation
Capacity = temperature of water
concentration = weird combination of off gassing and capacity
That leaves open the possibility that pearling of oxygen is less likely to occur in a cold water tank, and that contrary to what some other users were saying, higher CO2 capacity in cold water would not matter.
Unrelated to pearling but but does capacity affect solubility.This is what I figured. So in that case, I'm assuming that temperature does not factor into CO2 levels because our tank are never fully saturated with CO2 anyway, so the capacity is never reached. A saturated aquarium would basically be full of seltzer.
That leaves open the possibility that pearling of oxygen is less likely to occur in a cold water tank, and that contrary to what some other users were saying, higher CO2 capacity in cold water would not matter.
I think we all know colder water holds more capacity for dissolved gasses and assume that since we cannot easily measure o2 co2 saturation that cold water is generally preferred but this is unrelated to diffusion or solubility.
The below graph shows solubility of a given gas is different at different temperatures and that co2 is much more effected. This is solubility, not capacity.
https://www.chem.fsu.edu/chemlab/chm1046course/solubility.html
Aw man, what a great thread! I had never considered this before. I have been slowly lowering the temperature of my tank to up co2 levels in my tank. Will be following along with this thread.
Ahah! So it's not just capacity! That's very interesting. As you note, though, probably not related to pearling.Unrelated to pearling but but does capacity affect solubility.
I think we all know colder water holds more capacity for dissolved gasses and assume that since we cannot easily measure o2 co2 saturation that cold water is generally preferred but this is unrelated to diffusion or solubility.
The below graph shows solubility of a given gas is different at different temperatures and that co2 is much more effected. This is solubility, not capacity.
https://www.chem.fsu.edu/chemlab/chm1046course/solubility.html
I've moved away from heating all of my tanks, so this is great news to me.
I thought of you when I first posted this because I recalled a thread you posted a few months back about making a scape full of only the most pearling-prone plants.Aw man, what a great thread! I had never considered this before. I have been slowly lowering the temperature of my tank to up co2 levels in my tank. Will be following along with this thread.
How would this affect any fish or other critters in the tank,Aw man, what a great thread! I had never considered this before. I have been slowly lowering the temperature of my tank to up co2 levels in my tank. Will be following along with this thread.
Not very much at all, im just talking lowering it from like 80 to 77, just a few degrees, also doing it to lower the metabolism of the fish.. I have always ran my tank a little warm, im learning at closer to 75 is better.How would this affect any fish or other critters in the tank,
Regarding solubility, saturation and rates somewhere in there.
The easy way I learned about solubility in water is : Warmer means more solids, colder means more gas.
It is perhaps more easy to explain with solids as we can see them as opposed to gas, but the same thing happens just the other direction. A chemical that gives headaches to aquarists is K2SO4. Add 120g in 1L in warm 30°C water and it entirely dissolves (according to a quick search on wikipedia). Put that same water in a fridge and take it out at 6°C and you will notice a lump of K2SO4 at the bottom. 120g/L is the saturation point of K2SO4 in water at 25°C at 1atm. This represents the maximum concentration at those particular parameters, add more and it will not dissolve it will stay a solid.
Solubility is the ability, and the concentration needed to form a saturated solution (English language, not my fault). So the second parts means solubility=saturation point. From wikipedia CO2 Solubility in water:1.45 g/L at 25 °C (77 °F), 100 kPa. 1,45g/L means 1450ppm.... now look at my previous post, look at the link Attackturtle posted... Make sense, yes ?
I think Attackturtle wanted to mention Rate of dissolution . Shortly, the further you are from saturation point the faster you get to dissolve your product, thermodynamics stuff.
For us, the difference is likely to be insignificant in saving CO2 amount. Other factors such as surface agitation and that photosynthesis thing make a much larger dent as 5°C or Fahrenheit
The easy way I learned about solubility in water is : Warmer means more solids, colder means more gas.
It is perhaps more easy to explain with solids as we can see them as opposed to gas, but the same thing happens just the other direction. A chemical that gives headaches to aquarists is K2SO4. Add 120g in 1L in warm 30°C water and it entirely dissolves (according to a quick search on wikipedia). Put that same water in a fridge and take it out at 6°C and you will notice a lump of K2SO4 at the bottom. 120g/L is the saturation point of K2SO4 in water at 25°C at 1atm. This represents the maximum concentration at those particular parameters, add more and it will not dissolve it will stay a solid.
Solubility is the ability, and the concentration needed to form a saturated solution (English language, not my fault). So the second parts means solubility=saturation point. From wikipedia CO2 Solubility in water:1.45 g/L at 25 °C (77 °F), 100 kPa. 1,45g/L means 1450ppm.... now look at my previous post, look at the link Attackturtle posted... Make sense, yes ?
I think Attackturtle wanted to mention Rate of dissolution . Shortly, the further you are from saturation point the faster you get to dissolve your product, thermodynamics stuff.
For us, the difference is likely to be insignificant in saving CO2 amount. Other factors such as surface agitation and that photosynthesis thing make a much larger dent as 5°C or Fahrenheit
Thank you for all of the wonderful answers!
1 - 16 of 16 Posts
- This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
The Planted Tank Forum
A forum community dedicated to Aquatic tank owners and enthusiasts. Come join the discussion about flora, fauna, health, housing, filters, care, classifieds, and more!
Full Forum Listing
Explore Our Forums
Recommended Communities
