I have a debate on another site about the effects of pH changes due to CO2. Has anybody ever had any adverse effects on fish traceable to the pH change caused by CO2. (I don't mean that your fish suffocated when you added to much CO2. Thanks in advance
CO2 and pH
- Thread starter Canuck
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www.theplantedtankfaq.com
Might help you out. Check out the CO2 section. I've attempted to explain there why pH changes caused by CO2 don't harm fish.
You have to understand the basics of water chemistry.
Might help you out. Check out the CO2 section. I've attempted to explain there why pH changes caused by CO2 don't harm fish.
You have to understand the basics of water chemistry.
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what if your water is extremely soft, has very little or no buffering capacity, and a lower pH (low 6's) to begin with? then could it have adverse effects?
Simple:
Use CO2 and then drive the pH down one full unit.
Say from 7.4 to 6.4.
Use only CO2 to do this. No acid buffers, peat extract etc.
Now do a massive water change with the same tap water you used to start with. Say 80%.
You should have a change of about 0.8pH units and if you refill on a small tank, you can do this in under 1 minute.
Clearly a rapid change.
Result: healthy fish.
Many folks have been doing large frequent water changes in conjunction with CO2 dosing for decades. No ill effects have ever been observed, no diseases, not signs of stress.
Now try this, use baking soda to drive the pH from say 7.0 to 8.0 in under 1 minute and watch your fish die rapidly.
Why?
Baking soda is salt, it increases the TDS, the EC etc. CO2 is not a salt and causes no osmotic shock.
Most pH related issues are osmotic related, not pH in and of it's self.
Fish have the ability to deal with gas exchange in their blood(think O2/CO2 like in our blood vs injection high salt or removing all the salts) at very fast rates and the external versus the internal concentrations do not apply to the same degree as TDS/EC/salt/salinity etc. They can adjust slowly for salts also, but not rapidly.
Simpkle observations of tanks, such as all the ADA tanks show that weekly 50% water changes have no adverse impacts for over 20 years on internally thousands of tanks, if pH change due to CO2 alone is bad, why do we not see more issues?
If you have a hypothesis, test it. Then you have a much better idea.
Clearly whoever is claiming that pH alone from CO2 is the cause of the issues, has not never done so in a careful manner.
Adding too much CO2 can gas the fish, but that is O2/CO2 exchange/respiration related, not pH related.
Some that are not so careful mistake that for pH effects.
Regards,
Tom Barr
Use CO2 and then drive the pH down one full unit.
Say from 7.4 to 6.4.
Use only CO2 to do this. No acid buffers, peat extract etc.
Now do a massive water change with the same tap water you used to start with. Say 80%.
You should have a change of about 0.8pH units and if you refill on a small tank, you can do this in under 1 minute.
Clearly a rapid change.
Result: healthy fish.
Many folks have been doing large frequent water changes in conjunction with CO2 dosing for decades. No ill effects have ever been observed, no diseases, not signs of stress.
Now try this, use baking soda to drive the pH from say 7.0 to 8.0 in under 1 minute and watch your fish die rapidly.
Why?
Baking soda is salt, it increases the TDS, the EC etc. CO2 is not a salt and causes no osmotic shock.
Most pH related issues are osmotic related, not pH in and of it's self.
Fish have the ability to deal with gas exchange in their blood(think O2/CO2 like in our blood vs injection high salt or removing all the salts) at very fast rates and the external versus the internal concentrations do not apply to the same degree as TDS/EC/salt/salinity etc. They can adjust slowly for salts also, but not rapidly.
Simpkle observations of tanks, such as all the ADA tanks show that weekly 50% water changes have no adverse impacts for over 20 years on internally thousands of tanks, if pH change due to CO2 alone is bad, why do we not see more issues?
If you have a hypothesis, test it. Then you have a much better idea.
Clearly whoever is claiming that pH alone from CO2 is the cause of the issues, has not never done so in a careful manner.
Adding too much CO2 can gas the fish, but that is O2/CO2 exchange/respiration related, not pH related.
Some that are not so careful mistake that for pH effects.
Regards,
Tom Barr
As long as the fish where adapted to low KH, no.
CO2 added to tanks even with no KH still have no issues.
I can add the same amount of CO2, say 30ppm to a tank with a KH of 2.
If I maintain this same rate of CO2 addition, but remove the KH for the most part, the CO2 amount in solution is still the same. I can no longer measure it with pH/KH relationships, but it's still the same.
Two glass fill jars, one with Hard water and the other with DI water sitting out on a table for a a couple of days will have the exact same CO2 concentration.
The harder water glass will have more total DIC, some as KH and the rest as CO2, the DI water will have only CO2.
But both will be exactly the same. We do not see issues in nature from large shifts in pH due to CO2 uptake and diffusion either, tidepools get 2 full pH units in a few hours, same for vegetated lakes/shallow ponds. You can have 2 to 4 pH units in some of these systems daily, and they have fish etc.
Most of the lakes in FL fall under that grouping, the world's best Bass fishery.
Regards,
Tom Barr
Thanks Rex for the link and Tom for the experiment. I do that one at least once a week but never thought of it as a demonstration. If you haven't voted and have an opinion please do, at this point the number of votes leaves quite a large statistical error.
Thanks
Thanks
Sorry I do not see my choice up there
So no comment. hehe
Okay, I did vote. Now given those 3, which was it?
Hehe
Regards,
Tom Barr
I've observed negative impact on fish with pathological outcome when the variable was just CO2 mediated pH changes.
50% water change weekly with the following observations:
During refill of the tank, refill water temp is closely monitored to match tank temp in both cases. Same amount of de-chlor administered in both cases. Same procedure followed in both cases with ONE exception...
Good fishkeeper case:
CO2 bleed adjusted to ensure that refill water (pH 7.8) is compensated to match tank water (pH 7.0). Results: Fish are fat, dumb and happy (see fishkeeper bio)
Lazy fishkeeper case:
I don't adjust CO2 bleed and let tank pH climb to about 7.5 before tank water level reaches pH probe level and then let the solenoid CO2 blast it back down to 7.0. Result: Fish pale, behaviour is listless, 1 death, fin rot in multiple fish 1 day post.
Same procedure...same water pH...same de-chlor...same fish (minus 1)...same temp. Just the CO2 gyration. This is not just one or two data points. I must admit that the lazy fishkeeper scenario has occurred on >5 occasions with consistent problems each time to a varying degree.
From a biological point of view, pH swings are compensated for by the (human) body through two mechanisms...respiratory, and metabolic. Slow changes are metabolically handled by the kidneys through the control of bicarb (HCO3) in the blood. Acute changes are too rapid for the renal system and are compensated by the respiratory system. Biological systems don't react well to rapid changes in pH and our poor fishes are even more at risk than we are as their gills are in intimate contact with the water and changes in pH are rapidly conducted to the bloodstream. A good example of how rapid pH change feels is to hyperventilate for a minute or two. Two things happen...you're getting lots of O2 (which doesn't have a huge effect if you've ever been to an O2 bar) second, you're blowing off a ton of CO2 (which changes your blood pH really quick). After you've passed out and/or thrown up and your heart is racing and you're seeing spots you get the idea. I don't doubt that nature has some large pH swings that can be dealt with by aquatic lifeforms...only that they occur slowly enough that the organisms compensate for them successfully. Even then, I suspect that this involves some stress to the organism(s) and that those with marginal health/resistance may not successfully deal with it.
I am amazed at plantbrain's experience, nonetheless.
50% water change weekly with the following observations:
During refill of the tank, refill water temp is closely monitored to match tank temp in both cases. Same amount of de-chlor administered in both cases. Same procedure followed in both cases with ONE exception...
Good fishkeeper case:
CO2 bleed adjusted to ensure that refill water (pH 7.8) is compensated to match tank water (pH 7.0). Results: Fish are fat, dumb and happy (see fishkeeper bio)
Lazy fishkeeper case:
I don't adjust CO2 bleed and let tank pH climb to about 7.5 before tank water level reaches pH probe level and then let the solenoid CO2 blast it back down to 7.0. Result: Fish pale, behaviour is listless, 1 death, fin rot in multiple fish 1 day post.
Same procedure...same water pH...same de-chlor...same fish (minus 1)...same temp. Just the CO2 gyration. This is not just one or two data points. I must admit that the lazy fishkeeper scenario has occurred on >5 occasions with consistent problems each time to a varying degree.
From a biological point of view, pH swings are compensated for by the (human) body through two mechanisms...respiratory, and metabolic. Slow changes are metabolically handled by the kidneys through the control of bicarb (HCO3) in the blood. Acute changes are too rapid for the renal system and are compensated by the respiratory system. Biological systems don't react well to rapid changes in pH and our poor fishes are even more at risk than we are as their gills are in intimate contact with the water and changes in pH are rapidly conducted to the bloodstream. A good example of how rapid pH change feels is to hyperventilate for a minute or two. Two things happen...you're getting lots of O2 (which doesn't have a huge effect if you've ever been to an O2 bar) second, you're blowing off a ton of CO2 (which changes your blood pH really quick). After you've passed out and/or thrown up and your heart is racing and you're seeing spots you get the idea. I don't doubt that nature has some large pH swings that can be dealt with by aquatic lifeforms...only that they occur slowly enough that the organisms compensate for them successfully. Even then, I suspect that this involves some stress to the organism(s) and that those with marginal health/resistance may not successfully deal with it.
I am amazed at plantbrain's experience, nonetheless.
I've been doing it with Altums, discus, Apistos, AF Rift fish, with tetras and wild/rare fish of various sources without even any disease, stress etc for well over 15 years now.
I'm not sure how you are doing things, but I cannot attribute any stress to pH variation due to CO2.
If you gas your fish, then that's another issue, not related to pH and CO2, just too much CO2, see prior posting.
Why are you blasting CO2?
This is a CO2 gas issue where you added too much, and then had a spike and then the CO2 came back down.
measure of CO2 ppm is not easy, and O2 is also related to gassing your fish as well, low O2+ high CO2 = stress, high O2+ high CO2= mucy less stress.
Some taps have higher CO2 and O2, some less.
Some have variation in the KH as well.
