low riderr
New member
this may sound really dumb but if one was to dose oxygen into the tanks skimmer or just use an air stone would this help the ph?
question about oxygen
- Thread starter low riderr
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Randrew215
New member
CO2 impacts the pH because it is in an equilibrium reaction where it combines w/ H2O to form H2CO3 (carbonic acids), which itself breaks down to H+ and HCO3-. This is why increasing [CO2] lowers pH. I don't know of any similar reaction w/ O2. I don't know that adding O2 to the tank would do anything since it has such a large surface area to freely diffuse with the atmosphere, ie. I don't think you would have any appreciable ability to increase the [O2] in your tank unless you changed the atmospheric concentration within your home.
magdelan
Fish?
Nice post. In other words, CO2 can saturate water to drop PH, and O2 can only stabilize it, but at no point will adding more O2 be beneficial.
Adding O2 will not effect ph at all.
CO3: HCO3: CO2, H2O react and maintain equilibrium as they switch back and forth .
In freshwater CO2 draws H form the H20 and forms H2CO3 carbonic acid as it hydrolizes( CO2 + H2O --> H2CO3) The H2CO3 breaks down to H+ and bicarbonate HCO3-.
In salt water less than 1% of the CO2 goes to carbonic acid; the other 99+% skips the carbonic acid step and shows up as HCO3- and H+.
In either case the net effect is increased H+ which equals lower ph.
This post of mine in the chemistry forum a few months ago and Boomer's edit may help clarify the process:
Tom
"Baking soda is sodium bicarbonate. Carbonate is baked baking soda/soda ash. They are present in natural sea water at 20ppm of carbonate and 110 ppm of bicarbonate. Dosing bicarbonate (unbaked) may have a very small short term ph lowering effect. Dosing carbonate( baked) can raise ph significantly in the short run..
Carbonate (CO3), bicarbonate (HCO3) and carbonic acid(H2CO3) which is formed when CO2 hyrdolizes(CO2 plus H2O = H2 CO3) maintain proportions in sea water relative to the amount of H+(ph) . The H+ adsorbs to the CO3 and HCO3 neutralizing the acid.
More CO2 in the water means more carbonic acid and more H+ which shifts the balance toward more carbonic acid and more bicarbonate and less carbonate. Adding carbonate shifts it the other way.
Baked baking soda raises ph since adding it increases the amount of CO3 which has the capacity to take up 2 H protons,buffering the acid . The ph effect is generally short lived as CO2 equilibrating from the surrounding air enters the water and forms more carbonic acid with more H+ which shifts the balance of
CO3 : HCO3 : H2CO3
back to the right.
HCO3 bicarbonate has the capacity to take up only one H proton before becoming carbonic acid(H2CO3).CO3 has room for 2."
Well done
One thing to add, H2CO3 is almost non-extent in seawater < 1 %
There is very little of this going on
H2O + CO2 <---> H2CO3
It is mostly
H + HCO3- <---> H2O + CO2, the two act like the acid H2CO3. The H2CO3 reaction is skipped.
In Fw this H2O + CO2 <---> H2CO3 <---> H + HCO3- is more normal
CO3 : HCO3 : H2CO3
CO3 : HCO3 : H2O + CO2
CO3: HCO3: CO2, H2O react and maintain equilibrium as they switch back and forth .
In freshwater CO2 draws H form the H20 and forms H2CO3 carbonic acid as it hydrolizes( CO2 + H2O --> H2CO3) The H2CO3 breaks down to H+ and bicarbonate HCO3-.
In salt water less than 1% of the CO2 goes to carbonic acid; the other 99+% skips the carbonic acid step and shows up as HCO3- and H+.
In either case the net effect is increased H+ which equals lower ph.
This post of mine in the chemistry forum a few months ago and Boomer's edit may help clarify the process:
Tom
"Baking soda is sodium bicarbonate. Carbonate is baked baking soda/soda ash. They are present in natural sea water at 20ppm of carbonate and 110 ppm of bicarbonate. Dosing bicarbonate (unbaked) may have a very small short term ph lowering effect. Dosing carbonate( baked) can raise ph significantly in the short run..
Carbonate (CO3), bicarbonate (HCO3) and carbonic acid(H2CO3) which is formed when CO2 hyrdolizes(CO2 plus H2O = H2 CO3) maintain proportions in sea water relative to the amount of H+(ph) . The H+ adsorbs to the CO3 and HCO3 neutralizing the acid.
More CO2 in the water means more carbonic acid and more H+ which shifts the balance toward more carbonic acid and more bicarbonate and less carbonate. Adding carbonate shifts it the other way.
Baked baking soda raises ph since adding it increases the amount of CO3 which has the capacity to take up 2 H protons,buffering the acid . The ph effect is generally short lived as CO2 equilibrating from the surrounding air enters the water and forms more carbonic acid with more H+ which shifts the balance of
CO3 : HCO3 : H2CO3
back to the right.
HCO3 bicarbonate has the capacity to take up only one H proton before becoming carbonic acid(H2CO3).CO3 has room for 2."
Well done
One thing to add, H2CO3 is almost non-extent in seawater < 1 %
There is very little of this going on
H2O + CO2 <---> H2CO3
It is mostly
H + HCO3- <---> H2O + CO2, the two act like the acid H2CO3. The H2CO3 reaction is skipped.
In Fw this H2O + CO2 <---> H2CO3 <---> H + HCO3- is more normal
CO3 : HCO3 : H2CO3
CO3 : HCO3 : H2O + CO2
low riderr
New member
thanks guys for the answers,kinda figured it would be a no. but i had to ask
Nice post. In other words, CO2 can saturate water to drop PH, and O2 can only stabilize it, but at no point will adding more O2 be beneficial.
Yes, very good post.
Oxygen has no direct benefit to the ph at all not even ph stabilization.
CO2 saturation that may occur is transient since it will interact with carbonate and bicarbonate and the extra H+ it ultimately adds will lower ph.It will also equilibrate in some variable period of time with the air around the tank.
Oxide /hydroxide like the OH-- incorporated in (CO3--) buffers ph since the O-- can take up H+
Think of it this way.
The ocean relies the air around it for dissolved levels of athmospheric gases: nitrogen, oxygen, argon and carbon dioxide and other trace gases. The levels of dissolved gases in seawater( eg.: 100ppm CO2 ,including carbonate and bicarbonate ;10.7ppm N2;6.6ppm O2) are relatively constant in the vastness of the ocean but are no so much so in small closed systems like aquariums.
Gas exchange where the water meets the air in aquariums equilibrates gases dissolved in water with the air but at any one time a number of variables and interactions are in play.
The transient gas soup in a small closed system like an aquarium will have a recipe with ingredients that change by the instant. Slow gas exchange, high house air CO2 , CO2 additions from organisms, shifts in CO2 from carbonate to bicarbonate to carbonic acid , variable O2 depletion by organisms, O2 addition via photosynthesis and NO2 addition from anaerobic digestion are a few examples of the ongoing seasoning of this soup.
Yes, very good post.
Oxygen has no direct benefit to the ph at all not even ph stabilization.
CO2 saturation that may occur is transient since it will interact with carbonate and bicarbonate and the extra H+ it ultimately adds will lower ph.It will also equilibrate in some variable period of time with the air around the tank.
Oxide /hydroxide like the OH-- incorporated in (CO3--) buffers ph since the O-- can take up H+
Think of it this way.
The ocean relies the air around it for dissolved levels of athmospheric gases: nitrogen, oxygen, argon and carbon dioxide and other trace gases. The levels of dissolved gases in seawater( eg.: 100ppm CO2 ,including carbonate and bicarbonate ;10.7ppm N2;6.6ppm O2) are relatively constant in the vastness of the ocean but are no so much so in small closed systems like aquariums.
Gas exchange where the water meets the air in aquariums equilibrates gases dissolved in water with the air but at any one time a number of variables and interactions are in play.
The transient gas soup in a small closed system like an aquarium will have a recipe with ingredients that change by the instant. Slow gas exchange, high house air CO2 , CO2 additions from organisms, shifts in CO2 from carbonate to bicarbonate to carbonic acid , variable O2 depletion by organisms, O2 addition via photosynthesis and NO2 addition from anaerobic digestion are a few examples of the ongoing seasoning of this soup.
