Baking soda and Ph?

[Personage]

Has anyone any info on the use of baking soda to raise Ph after a 25% water change. The stuff they sell at Petco is costly.


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[dalto]

baking soda will raise pH and KH. I think it is a buffer with a preference of pH 8.2 What is your current pH and what are you trying to move it to?

 

[Cthulhu]

IMO you should use calcium carbonate instead of sodium bicarbonate.

 

[Mebbid]

What does your ph run that you need to adjust it?

 

[PNWaquarist]

IMO you should use calcium carbonate instead of sodium bicarbonate.

Calcium carbonate is only sparingly soluble and takes a while to dissolve. Baking soda (sodium bicarbonate) is much more soluble and will raise your pH almost immediately.

I typically add a little to raise my tank pH to 8 when I'm cycling. The way I do this is to scoop out an ounce or two of tank water, add 1/4-1/3 of a teaspoon of baking soda, stir to dissolve, and pour back into your tank. Wait 15 min for the filter to circulate it and then measure the tank pH. Repeat as necessary. Do not add solid baking soda directly to a stocked tank.

 

[trennamw]

Baking soda in my experience is a very temporary solution.

I'm fairly certain it adds KH. KH doesn't directly raise pH. It neutralizes things that reduce pH.

Usually, messing with pH by means other than a water change is unnecessary and does more harm than good.

In some extreme situations (fish with special pH needs or tapwater that's odd) it's good to adjust.

Tell us more about the whole situation and we can better help.


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[PNWaquarist]

Baking soda in my experience is a very temporary solution.

I'm fairly certain it adds KH. KH doesn't directly raise pH. It neutralizes things that reduce pH.

KH is a measurement of the total amount of carbonate (CO2, bicarbonate ion, and carbonate ion) in water. Because this is the predominant buffering system in tap water, it is also a good measurement of the water's buffering capacity.

Baking soda is sodium bicarbonate, which acts as a weak base in tap water. Adding a weak base to tap water will raise the pH.

 

[trennamw]

KH is a measurement of the total amount of carbonate (CO2, bicarbonate ion, and carbonate ion) in water. Because this is the predominant buffering system in tap water, it is also a good measurement of the water's buffering capacity.

Baking soda is sodium bicarbonate, which acts as a weak base in tap water. Adding a weak base to tap water will raise the pH.

That's right you mentioned it the other day. I'm still confused obviously.

If it doesn't raise KH that explains why it doesn't work well.


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[Personage]

I'm not really having any Ph issues and my tank seems to be doing really well. I mostly use the test strips and Ph seems to read about 6.6 however sometimes after a water change it drops somewhat. I was just looking for a less expensive way of Ph control over those little packets they sell. It's cheaper to buy Filet Mignon.
I try to leave the tank alone as much as possible. Don't want to tamper with a tank that is well balanced.
I have substrate under gravel with all live plants, a 100 gal capacity canister filter for a 55 gal tank. The thriving community consists of 16 Neon Tetras, 6 Gold Tetras, 6 24k Gold, 6 Long Fin Zebra Danio, 4 Albino Cory Cats, 4 Kuhli Loach, 2 Dwarf African Frogs, 3 Nerite Snails and a Mystery Snail.
The 24k and Danio cruise the surface while the Tetras stay midrange and the bottom feeders and snails do the rest.
I use API Leaf Zone, Co2 Booster and Stress Zyme. Feeding very sparingly helps a great deal to keep the water crystal clear. I'm working on getting a photo in soon.
Thanks to everyone for your responses!! ???


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[trennamw]

You probably don't need the stress zyme. Once a tank is cycled, why add bacteria?

Why are you adding anything to the water for pH? Is it in reaction to this drop at water changes, or is it what is causing it? Is your tapwater slightly acidic too?

In response to PNW ... I've spent some of this evening reading up and I'm still not sure I believe it's useful to consider baking soda a base in this setting.

What I'm gathering, and I could be wrong but I think I'm on the right track ...

Baking soda in the box is a salt. It can react with both acids and bases.

Combined with distilled water with a pH of about 7.5, the result is slightly more basic. That is, the solution of baking soda and pure water is basic ... This doesn't mean baking soda is a base.

In water with a pH of about 8, baking soda has some efficacy as a buffer, to keep pH where it is. But not a lot.

If baking soda were a base, surely it would continue to raise pH the more you add? Since it is preferential to a pH of 8, sounds like a buffer?

So I still think at this moment it's easier to understand baking soda as a buffer in aquariums, albeit a weak one.

The OP might look into DIY Chiclid salts. I believe these combine baking soda, Epsom salt, and ice melt product, to raise KH and GH. The byproduct of which might be a more stable pH.


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[fishliker]

I have used a little bag of coral in with the filter for several years to raise pH. I have seen that recommended here before. It works slowly and well. I had used baking soda earlier when I first started with fish and did find it to be very temporary and not so stable. Don't know why, but after I got my 2 new tanks up and running this summer, the pH started running a little high and I have slowly been removing a little coral until I don't have any now in either tank. If you are interested, let me know and I will look up how much I started with etc. it's crushed coral.


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[Mebbid]

You probably don't need the stress zyme. Once a tank is cycled, why add bacteria?

Why are you adding anything to the water for pH? Is it in reaction to this drop at water changes, or is it what is causing it? Is your tapwater slightly acidic too?

In response to PNW ... I've spent some of this evening reading up and I'm still not sure I believe it's useful to consider baking soda a base in this setting.

What I'm gathering, and I could be wrong but I think I'm on the right track ...

Baking soda in the box is a salt. It can react with both acids and bases.

Combined with distilled water with a pH of about 7.5, the result is slightly more basic. That is, the solution of baking soda and pure water is basic ... This doesn't mean baking soda is a base.

In water with a pH of about 8, baking soda has some efficacy as a buffer, to keep pH where it is. But not a lot.

If baking soda were a base, surely it would continue to raise pH the more you add? Since it is preferential to a pH of 8, sounds like a buffer?

So I still think at this moment it's easier to understand baking soda as a buffer in aquariums, albeit a weak one.

The OP might look into DIY Chiclid salts. I believe these combine baking soda, Epsom salt, and ice melt product, to raise KH and GH. The byproduct of which might be a more stable pH.


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Its not a large one, but it does have some impact on ph. It is primarily a buffer though.

 

[PNWaquarist]

That's right you mentioned it the other day. I'm still confused obviously.

If it doesn't raise KH that explains why it doesn't work well.

Baking soda (sodium bicarbonate) does raise KH because it contributes to the carbonate buffering system.

Baking soda in the box is a salt. It can react with both acids and bases.

Combined with distilled water with a pH of about 7.5, the result is slightly more basic. That is, the solution of baking soda and pure water is basic ... This doesn't mean baking soda is a base.

Sodium bicarbonate is indeed a weak base in water, as is evidenced by the fact that it makes the water more basic.

The acid/base equilibrium of the carbonate buffer system is somewhat complex:

CO2 <=> H2CO3 <=> HCO3- + H+ <=> CO3-- + H+

CO2 and H2CO3 predominate at < pH 6.5
HCO3- predominates between pH 6.5 and 10
CO3-- predominates at > pH 10

Carbon dioxide dissolves into and reacts with water to form carbonic acid (H2CO3). Carbonic acid is unstable and loses a proton (H+) to give bicarbonate ion (HCO3-). This is the predominant species at tank pH. At higher pH, bicarbonate loses another proton to give carbonate ion (CO3--).

If you do some reading on buffers, you'll note that they have two components: a conjugate acid and a conjugate base. In the aquarium, carbonic acid is the conjugate acid and bicarbonate (HCO3-) is the conjugate base. Addition of the conjugate acid will make the solution pH more acidic. Addition of the conjugate base will make the solution more basic (which is why sodium bicarbonate raises tank pH). Addition of either the conjugate acid or conjugate base will increase the buffering capacity of the tank.

 

[trennamw]

Its not a large one, but it does have some impact on ph. It is primarily a buffer though.

Right. Maybe it's just semantics but I think it's important to understand the difference between a substance directly raising pH, and a substance being a buffer which results in a higher pH after it is added.

I don't contest that baking soda in water is a basic solution. But I'm agreeing with the sources online that say this is because baking soda is a buffer, not a base. PNW in many ways we are saying the same thing.

Coral also does not necessarily raise pH. It raises KH, which buffers pH.

Back to the topic at hand ... The original poster ... It'd be helpful to know why you're trying to raise your pH at all, and what the tapwater measures.

At any rate baking soda alone is unlikely to be what you need.



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[PNWaquarist]

I don't contest that baking soda in water is a basic solution. But I'm agreeing with the sources online that say this is because baking soda is a buffer, not a base. PNW in many ways we are saying the same thing.

Unlike the sources online, I have a couple of chemistry degrees, publications in peer-reviewed journals, and years of teaching experience under my belt. So you'll have to trust me when I say that baking soda (sodium bicarbonate) acts as a weak base in water near neutral pH. Sodium bicarbonate will pick off protons from water molecules, which causes the solution pH to rise. By itself, sodium bicarbonate is not a buffer, but will protonate to form carbonic acid under tank conditions. The bicarbonate/carbonic acid/CO2 system acts as a buffer in the aquarium.

Coral also does not necessarily raise pH. It raises KH, which buffers pH.

Coral contains calcium carbonate, which is slightly soluble in water. Over time it will dissolve in water and the carbonate ion will pick up protons to form bicarbonate ion. Because it picks up protons from water molecules, it acts as a base under tank conditions and raises the pH. And because much of the dissolved carbonate ion is converted to bicarbonate ion, the bicarbonate/carbonate buffer system is established. You are correct that, as more calcium carbonate dissolves in water, the solution KH and buffering capacity are both increased.

 

[fishliker]

Unlike the sources online, I have a couple of chemistry degrees, publications in peer-reviewed journals, and years of teaching experience under my belt. So you'll have to trust me when I say that baking soda (sodium bicarbonate) acts as a weak base in water near neutral pH. Sodium bicarbonate will pick off protons from water molecules, which causes the solution pH to rise. By itself, sodium bicarbonate is not a buffer, but will protonate to form carbonic acid under tank conditions. The bicarbonate/carbonic acid/CO2 system acts as a buffer in the aquarium.



Coral contains calcium carbonate, which is slightly soluble in water. Over time it will dissolve in water and the carbonate ion will pick up protons to form bicarbonate ion. Because it picks up protons from water molecules, it acts as a base under tank conditions and raises the pH. And because much of the dissolved carbonate ion is converted to bicarbonate ion, the bicarbonate/carbonate buffer system is established. You are correct that, as more calcium carbonate dissolves in water, the solution KH and buffering capacity are both increased.

Thanks for explaining that, about the coral. I knew it worked, didn't know why...


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[PNWaquarist]

Thanks for explaining that, about the coral. I knew it worked, didn't know why...

 

[Personage]

Well I guess I should've mentioned that I just replaced my RENA Filstar canister filter with a new leaky Plen-Plax Cascade 1000 due to aged gaskets and O rings. While I'm refurbishing the RENA I have the Cascade to relieve the pressure of immediate repair.
I could have reused the bio medium but considering the problems I've had with those Insidious Malaysian snails I decided to start over with new medium, ergo; having to add the Stress Zyme and keep a close Eye on Ph level. The tank is doing well without any loss of life but I just don't want to spend 5 bucks on a few ounces of Ph adjuster at the Pet__ store. Getting clearer?


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[PNWaquarist]

Well I guess I should've mentioned that I just replaced my RENA Filstar canister filter with a new leaky Plen-Plax Cascade 1000 due to aged gaskets and O rings. While I'm refurbishing the RENA I have the Cascade to relieve the pressure of immediate repair.
I could have reused the bio medium but considering the problems I've had with those Insidious Malaysian snails I decided to start over with new medium, ergo; having to add the Stress Zyme and keep a close Eye on Ph level. The tank is doing well without any loss of life but I just don't want to spend 5 bucks on a few ounces of Ph adjuster at the Pet__ store. Getting clearer?

Keep in mind that baking soda will increase your tank water pH. If you want to stay around pH 6.6 (or below pH 7), I wouldn't recommend baking soda.

I've never used the over-the-counter buffers and don't know what your options are in that area. If you decide to go that route, make sure that the product buffers near your desired pH.

 

[trennamw]

Unlike the sources online, I have a couple of chemistry degrees, publications in peer-reviewed journals, and years of teaching experience under my belt. So you'll have to trust me when I say that baking soda (sodium bicarbonate) acts as a weak base in water near neutral pH. Sodium bicarbonate will pick off protons from water molecules, which causes the solution pH to rise. By itself, sodium bicarbonate is not a buffer, but will protonate to form carbonic acid under tank conditions. The bicarbonate/carbonic acid/CO2 system acts as a buffer in the aquarium.



Coral contains calcium carbonate, which is slightly soluble in water. Over time it will dissolve in water and the carbonate ion will pick up protons to form bicarbonate ion. Because it picks up protons from water molecules, it acts as a base under tank conditions and raises the pH. And because much of the dissolved carbonate ion is converted to bicarbonate ion, the bicarbonate/carbonate buffer system is established. You are correct that, as more calcium carbonate dissolves in water, the solution KH and buffering capacity are both increased.

It's good to hear your credentials, never know what's what around here.

I was reading articles from journals sent to me by a friend who is a chemical engineer, when I asked him the question. What I'm seeing is even the well credentialed chemistry experts have different ways of phrasing the properties of baking soda.

Again I think it's hitting semantics, and what needs to be emphasized in this context ... That a solution of baking soda and pure oh neutral water is a weak base may be correct, but is not so useful here. Nor is the phrase "baking soda raises pH."

Thanks for the lesson! Wonder if you were my chem teacher at LCC ...


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