Baking soda & Washing soda ? Brad?

[Doug]

Hi Brad,

In a previous post you said:

I add Arm and Hammer Baking soda in 6 parts and Arm and Hammer Washing soda in one part together for a home made buffer. One heaping teaspoon per 25 gallons raises DKH 1 point. The two together makes a solution PH of about 8.0.

and I am hoping that you can clarify something for me. Do you mix the 6 parts baking soda and one part washing soda in powder form and then add a tsp of the combined powder to the makeup water?

I think that is what you meant but I am just trying to make sure.

TIA

Doug

 

[Aaron Shelley]

^

 

[Brad Ward]

Doug,

That is correct. The Washing soda (Sodium Chloride)has a lower ph than the Baking soda (Sodium Bicarbonate)which stabilizes the ph at around 8.0. These are the two main ingredients in commercial buffers that you buy from the aquarium suppliers. I just pour it in the overflow and let it get mixed by the Protien skimmer pump and then the Main recirc pump. Those ingredients along with pickling lime make the Supermarket my one stop shop.

hth,

Brad

 

[Aaron Shelley]

Is washing soda (sodium Chloride), just good 'ol fashion Mortons' table salt?

OR is it actually sold as "washing soda"?

Tank ya very much!

 

[Brad Ward]

Aaron,

No. It is made by Arm and Hammer, and found in the laundry detergent section of the Supermarket.

Brad

 

[Mutagen]

Brad,

You're using the same formulation I once used, but you have the chemistry somewhat misrepresented. For those who wish to use your technique, allow me to clarify.

Washing soda is NOT sodium chloride! It is sodium carbonate.
It does not have a lower pH in water than baking soda, in fact it is much higher. Sodium chloride really is the Morton salt found in the seasoning section and is not useful for reefing purposes.

Baking soda alone will cause the water pH to drop. That is why adding the washing soda helps, it raises the pH.

If you can't find washing soda you cna make your own by baking some baking soda on a cookie sheet for about 1/2 hour at 450 F in the oven. Then mix unbaked and baked together in approximately the proportions Brad suggests.

Good reefing, Mutagen

 

[FishBait]

Well I must say I found this stuff interesting, but one statement Mutagen made has me confused. Please explain to me why baking soda (sodium bicarbonate) will cause your pH to drop. Aren't bicarbonates one of the main buffering compounds found in natural aquatic systems? I have had many of my customers use baking soda in an attempt to raise their pH, and it does so quite well. Perhaps are u talking about a long-term stability? Just curious about this is all.

 

[Doug]

Hi Brad,

Thanks for your help! I thought that was what you meant but I just wanted to make sure.

Hi Mutagen,

Thanks for the additional clarification.

I have used many of the commercial buffer products like Seachem and Kent but it seems that they are skewed on the sodium carbonate side which causes my pH to go too high. For some odd reason the pH in my tanks are higher than most and the alk is lower and I am hopeful that the combination of the baking soda and washing soda will help me find a happy medium. I can always adjust up or down the amount of each powder based on my pH and alk for a particular time frame.

Thanks again.

Doug

 

[Frisco]

Maybe this will help - DBW has a pretty good intro to alkalinity and buffering: http://www.ozreef.org/reference/alkalinity.html

In particular check out the following chart: http://www.ozreef.org/reference/images/alkalinity_ph.html

 

[MIKE]

Hi Doug,

How's things?

Are you sure the ph elevation is due to the buffer? If you have alot of photosynthesis in your tank, you might also skew ph to the higher side, and unless it's pretty high it's not really a big problem. If that's the case, even if you adjust the mix of buffers, the ph shift will only be temporary. Whenever I've used the SuperBuffer (don't know about the Seachem), it doesn't seem to affect ph.

BTW, you can also obtain sodium carbonate from pool/spa suppliers as a Ph Up product (read the label) real cheap.

 

[Doug]

Hi Mike,

Glad to see ya!

I have noticed that if I use the Superbuffer it will keep making the pH continue to rise from 8.25 in the morning to 8.45+ at the end of the day on the 90g tank. If I stop using it the pH will suddenly fall off to 7.95 in the morning to 8.25 or so at the end of the day. The issue is that it doesn't seem to have a good impact on helping my alkalinity come up.

On my 75g tank the pH is always high and when I use Superbuffer on it the pH will climb to 8.6+ at the end of the day.

The only other thing that I can think of is that my water might be out of ionic balance and maybe it is utilizing more of one buffer component than the others which is giving me the elelvated pH levels.

Thanks.

Doug

 

[Brad Ward]

Whoops! Thanks for the correction. I meant carbonate. It does however have small quantities of salts (chlorides) like all buffers do, and can raise salinity over time.

Thanks again,

Brad

 

[WaterKeeper]

While the use of a baking soda-soda ash buffer serves well in an emergency one caveat should be noted. Soda ash, sodium carbonate, can convert non-carbonate hardness (i.e. calcium chlorides and sulfates) to insoluble calcium carbonate. While this is not a problem most of time it can be if one adds KW in large amounts. Here the amount of calcium carbonate precipitated can be significant. Symptoms of this happening are an elevated pH while both calcium and total alkalinity decline. In extreme cases "snowflake" precipitation and substrate cementation may occur. For routine use a magnesium/calcium bicarbonate buffer will serve one better.

 

[Mutagen]

This subject ALWAYS creates confusion, probably because most reef keepers are not chemists. Hopefully, this will help!

Additive___________________buffer effect______________pH effect

sodium carbonate___________adds to buffer_____________adds to pH

sodium bicarbonate_________adds to buffer_____________subtracts from pH

sodium chloride____________no change__________________no change

calcium hydroxide__________adds to buffer_____________adds to pH

calcium chloride____________no change__________________no change

CO2______________________no change__________________lowers pH

calcium bicarbonate________ adds buffer_______________lowers pH


Now, what is what?

Soda ash = sodium carbonate = washing soda = baked baking soda = Na2CO3
Sodium bicarbonate = baking soda = NaHCO3
Calcium hydroxide = kalkwasser = pickling lime = quicklime = hydrated lime = Ca(OH)2
Calcium chloride = ice melt in some areas = CaCl2
Calcium bicarbonate = calcium reactor effluent

Alkalinity is the ability to neutralize an acid until the pH gets to about 4.3. That's the point that all carbonates are transformed into CO2.

A buffered solution is a solution which resists changes in pH when either an acid or a base is added.

In salt water systems, the compounds which provide the acid neutralizing ability, the alkalinity, are the same compounds that provide the buffering ability. These compounds are the carbonates and bicarbonates.

In salt water systems, about 80% of the buffer is present as bicarbonate. The remainder is present as carbonate. This situation is NOT fixed. Adding or removing CO2 will shift the ratio of these two compounds. Adding baking soda, washing soda, or kalkwasser will also shift this ratio. If the bicarbonate ratio goes up, the pH goes down and vice versa. This is why adding baking soda makes pH drop. It initially increases the ratio of bicarbonate to carbonate.

This situation is increased in complexity as the tank water is always exchanging CO2 with the surrounding air. If the pH is low, the water will have a tendency to give up CO2 and this increases the pH. If the pH is high, the water will have a tendency to absorb CO2 and the pH will go down. This is why the pH does not stay low when baking soda is added. The problem is, the exchange of CO2 is very much slower than we can change the system by our various additives.

If the pH of your system is highly variable on a daily cycle, you should increase water circulation and especially make sure the surface tension of the tank water is broken. Most gas exchange occurs here at the surface and the layer of surface tension on still water creates a substantial barrier to gas exchange. Also, make sure your alkalinity is up around 3.5 meq/l as this will also help.

I will post the method to use your pH meter for alkalinity testing separately.


Hope this helps, Mutagen

 

[Doug]

Hi Mutagen,

Wow, Thanks for the info.

[arc]

Doug

 

[MIKE]

Hi Gang,

Mutagen, great post! Thanks a bunch!

Doug, my understanding of the Kent product is that it's not supposed to do that. Something's just not right with your situation. I'm wondering if you have a bum batch, or something is wrong with it? The fact that's it's not increasing your alkalinity is also of concern, unless you're not using enough. But if you're concerned about the ph rise, I can see why you might be a little shy.

Another thing I can think of is that your alkalinity is low enough (I didn't see if/where you posted the reading) that you are having a bit of a depressed ph without adding buffer (perhaps due to photosynthesis, co2 accumulation) and that when you add buffer, it's not actually "increasing" ph but rather "restoring" ph, as buffers in the system increase. The proof of this would be if you continued to add buffer despite a ph increase to the desired alkalinity level, but the ph did not continue to linearly increase beyond an initial increase. (this may be clear as mud, let me know if it doesn't make sense).

Another thing to always verify is the accuracy of your ph and alkalinity readings. If ph is off (and almost all methods are "off" somewhat), then when it's on the "high" side maybe it's not quite as high as you think. And while alkalinity test kits are generally pretty accurate, if the chemicals get old they lose accuracy. Even if you've not had it long, who knows how long it sat on the shelf somewhere (I've personally experienced this problem).

If I were in your position, I'd buy a new alkalinity kit (they're pretty cheap), and a new batch of SuperBuffer, or mix your own using the Brad receipe, and dose buffer until the alkalinity is where you want it. I'd probably put my hand over my eyes and not watch ph (just kidding). Once alkalinity is in shape, then I'd see where I was. I'm betting you'll find that when alkalinity is corrected that ph is actually fine.

Just some ramblings on your situation.

 

[MIKE]

Hi Mutagen

If you don't mind, I want to highlight this portion and be sure I understand it correctly:

This situation is increased in complexity as the tank water is always exchanging CO2 with the surrounding air. If the pH is low, the water will have a tendency to give up CO2 and this increases the pH. If the pH is high, the water will have a tendency to absorb CO2 and the pH will go down. This is why the pH does not stay low when baking soda is added. The problem is, the exchange of CO2 is very much slower than we can change the system by our various additives.

My understanding of this is that even when you add sodium carbonate (increases ph) or sodium bicarbonate (decreases ph), the change in ph is temporary, and with all things being equal, ultimately the ph will return to the it's equilibrium point based on that tanks co2 exchange. And, that all that can occur while the alkalinity actually increases. Am I reading this right?

 

[Mutagen]

Mike,

You got it precisely!

Mutagen

 

[Doug]

Hey Guys,

The light bulb just came on and I think I finally understand the point that you are making.

From the article that Frisco referenced, what Mike pointed out and Mutagen verified as I am reading it even if the carbonates and bicarbonates are out of whack they will reach a point of equalibrium and the pH will stabilze wherever it should be based upon the amount of lack of CO2?

Here is where I am still fuzzy.

Now the issue that I have is that even though the rise in pH is temporary is it still possible that it will go too high. The reason that I ask is because of the high Calcium and Alkalinity demand in my tank I need to add buffer more often, sometimes everyday, to keep it above 2.0meg.

Mike, you make a good point about the inaccuracy of measuring pH and I understand but I have both a Neptune pH/orp meter and a Neptune Aquacontroller Pro on the tank and both read a pH of 8.45 as I am typing this. I have also tested it before with the two different brands of test kits and they read 8.4 when the meters say 8.4 or more. I also agree that the batch of Kent SB could be bad but I have also noticed the same rise in pH when using the Seachem Reef Builder product and the Kent liquid SB. You are right about me being shy when adding the buffers when the pH climbs too high. I do stop adding it for a day or two and the pH does drop back down as does the Alkalinity.

Now do you think that if I continue to add the buffer daily will the tank never reach an equlibrium because of the constant additions? Or will it eventually reach a point where the pH will reach a limit and not climb higher?

Brad, have you noticed this same effect with your tanks or has your pH remained stable? And what is your normal pH readings it you test them?

Thanks for all your help everyone.

Doug

 

[MIKE]

Hey Guys,

From the article that Frisco referenced, what Mike pointed out and Mutagen verified as I am reading it even if the carbonates and bicarbonates are out of whack they will reach a point of equalibrium and the pH will stabilze wherever it should be based upon the amount of lack of CO2?

Here is where I am still fuzzy.

Now the issue that I have is that even though the rise in pH is temporary is it still possible that it will go too high. The reason that I ask is because of the high Calcium and Alkalinity demand in my tank I need to add buffer more often, sometimes everyday, to keep it above 2.0meg.

Hi Doug,

Ok, looks like your ph readings are as accurate as anyone's are likely to be. As I understand it, the answer to your first question is...yes.

In your second paragraph, yes ph can go "too high". But it's a relative thing....i.e. the higher the ph, the harder it will be to have calcium and carbonates stay in solution. OTOH (Harry Truman always said he was looking for a one handed economists ), unless ph really spikes quickly and high, I wouldn't worry about it much. I think as you dose buffer, ph will rise but hit a "ceiling", and not be problematic.

Given your particular tank, I would simply dose a balanced buffer until you get alkalinity where you want it. Dosing buffer every day, or even twice per day, wouldn't be all that unusual. The bottom line is that you need to dose it in such a way that you are daily making headway on increasing alkalinity, perhaps in small increments, but increasing it nonetheless. When alkalinity is around 3 meq., then you should have a pretty good idea about what the "maintenance" dose will be. You'll likely be surprised at just how much buffer is being consumed in your tank.

While you are doing that, don't be at all surprised if the calcium falls some. This would be expected and can be remedied by increasing the calcium dosage slightly and slowly if needed.

Man. I would guess that your tank is fully stocked, and really COOKIN'. To have those ph levels, and that carbonate usage, you must have lots of animals that are sucking up the carbonates big time. This isn't a problem except that you'll need to continually replenish! I would also suspect you must be having some pretty good growth rates? Most folks wish they had your problem!


[Edited by MIKE on 02-26-2001 at 09:16 PM]