Difference sodium bicarbonate/carbonate

[Tab28]

I know there is a difference. I think SC raises ph as well as alk. But for 2 part dosing which do you use for making dosing solution.

 

[Reefing Madness]

Sodium carbonite, is stronger on raising ALk, so not as much is needed, and in a 24hours span the PH will more than likely return to normal anyways.

 

[redfishbluefish]

Either one will provide the alkalinity you will need for your tank. The difference between the two is that Sodium Carbonate is used for tanks that have a pH on the lower side, while Sodium Bicarbonate is for tanks were pH is already high. When making up the solutions, Sodium Bicarbonate has much lower solubility then Sodium Carbonate, and is typically made up at half the strenght. A "standard" sodium bicarbonate solution is 1 1/8 cups made up to one gallon with RO/DI water, while a sodium carbonate solution is 2 cups (2 1/4 cups of sodium bicarbonate baked at 300 degrees for one hour results in sodium carbonate (ca 2 cups)), made up to one gallon with RO/DI water. The equivalence on these two solution is half that of the sodium carbonate. That is why you need twice the amount of a sodium bicarbonate solution to equal the sodium carbonate solution.


Wow, that's confusing. I hope you understand.


Dr. Randy Holmes Farley has THIS nice write-up on this whole thing.....Recipe 1, Part 2 versus Recipe 2, Part 2.

 

[Tab28]

Yes it is confusing. If ph in tank low end use SB after heating it or just use SC. If ph high end use SB without heating since that basically makes it SC. Hope i got that right. Or is it the opposite?

 

[redfishbluefish]

If you bake sodium bicarbonate (baking soda) in the oven for an hour or so, it is converted to sodium carbonate (soda ash). So after baking, you now have sodium carbonate. The Randy Recipe calls for 2 1/4 cups of sodium bicarbonate baked at 300 degrees for an hour. It wouldn't hurt to cook a bit longer, especially if this wasn't spread thin on something like a cookie sheet. Although you started with 2 1/4 cups, this "baked" material is now approximately 2 cups. SO if you already had sodium carbonate (like BRS soda ash), you only need to measure out 2 cups to the one gallon of RO/DI water. Hope this clarifies.


If pH in you tank is running low (say 8.1 or less, to pick a number), use the sodium carbonate solution.


If pH in you tank is running high (say higher than 8.1, to pick a number), use the sodium bicarbonate solution.

 

[beaslbob]

I know there is a difference. I think SC raises ph as well as alk. But for 2 part dosing which do you use for making dosing solution.

either.

the effect on pH is minimum if any.

my .02

 

[mcarroll]

Must agree with Bob that the effect on pH is minimal...and temporary. I vote for using PLAIN BAKING SODA.

Baking soda carries an extra CO2 molecule compared to sodium carbonate (aka washing soda). Consider that you're only adding a tiny amount to the system at any time and that this extra CO2 molecule is off-gassed/consumed by photosynthesis an average system in very short order. Last, a rise in pH like you might get from dosing washing soda is more likely to cause a problem (local precipitation) than a similar dip would cause, IME.

As far as one being "stronger", that should be irrelevant as you are creating your dosing solutions according to the Recipe 1 or 2 formula and dosing them according to your test results. How much quantity you dose ("strength") actually doesn't matter, does it?

I guess it may matter if you run an automated doser - Recipe 2 (plain baking soda) is easier to dose due to the lower impact on local pH and the dripping speed and drip-size can be larger. Effectively, Recipe 2 increases the resolution of your doser. Once your dosing rate gets up there (e.g. I manually dose about 200 mL of Recipe 2 each day) I actually recommend diluting the dosing solution a bit anyway since the quantity being added at any given dose is so large. I typically dilute by almost half. (And remember Recipe 2 is already half the relative strength of Recipe 1.....I'd dilute Recipe 1 even more.)

You will neither alleviate a high pH situation, nor cause a low pH issue by dosing baking soda as the alkalinity component of your two-part.

For that reason, I think it only makes sense to use plain baking soda if you're doing it yourself. Baking it in the oven is a waste of energy and time. (Just buy washing soda if using it seems that important.)

-Matt

P.S. If you do have a tank with persistently low pH of about 7.8 or lower, remember that's a different issue and alkalinity may not even be related. Alk has to be astronomically low to be the cause of a low-pH issue, and you may only see the low at night when photosynthesis is shut off and the corals are all respiring, throwing more CO2 in the water - the pH may actually spike high during the day. If pH is persistently low, more than likely (assuming the tank water is in at least decent shape) you would have too much CO2 building up in your house, which them dissolves into your tank water, lowering pH...an uncommon, but possible, scenario.

 

[Tab28]

I will be using a dosing pump. I am now dripping kalk. But it is not enough. I have to supplement more alk.

I do get the lower ph in AM. Around 7.8. Which is because i live in FL way to hot to open windows even at night.

 

[mcarroll]

There are ways of bringing in fresh air without opening a window...running your skimmer's air line outside in some way (be creative!) is common.

Also, consider running kalk+vinegar:
http://www.reefscapes.net/articles/breefcase/kalkwasser.html

-Matt