What happens chemically when i add bicarbinate of soda to my tank?

[Sebastian_Troy]

I have read online that instead of using expensive reef buffers I can add bicarbonate of soda, however I am
Struggling to pin down exactly how adding it alone helps, I mean sure it raises KH but not in a balanced way, or am I wrong, can anyone help?

 

[mr_X]

what do you mean not in a balanced way? you have to find out how fast you are using alk in order to determine how much to add. that's how you balance it.

Aquarium Chemistry: A Homemade Two-Part Calcium And Alkalinity Additive System — Advanced Aquarist's Online Magazine

 

[Sebastian_Troy]

By balanced I mean I'm adding bicarbonate only but the KH includes other compounds, some of which are important, so is adding purely bicarbonate pushing any equilibriums off where they should be?

 

[mr_X]

what other compounds are you speaking of? what do you think salt water alkalinity buffers are?

 

[Sebastian_Troy]

Well I don't know but I know what a buffer is, it is a reversible reaction, which means under normal circumstances it is reacting and reacting back constantly, if it is reacting forward and backward at the same rate it's equilibrium leaves it at 50:50 half of the reactants and half the products, this equilibrium can shift from side to side up till 100% either way at which point it cannot react further, the equilibrium opposes change to it's environment, so it cancels out change in say pH (a pH buffer),

Anyway I Think the main point was that bicarbonate as part of a buffer is only one half of the equilibrium (possibly only one part of one half) and adding too much of one side of the equilibrium without the other can push it too far to the other side for it to act as a buffer anymore,
you may understand buffers better than me buy that's a pretty rough idea of buffers if you didn't know

 

[mr_X]

all you are trying to do is raise alkalinity. adding baking soda will do this. adding more, will raise it more. adding less will raise it less. it's not going to stop like a ph buffer would. your calcium level will also change. those work hand in hand, as does magnesium.
if your problem is low alk, then add some baking soda and recheck....add again...and then you know what it took to raise it to your optimum range.
everyone's bio load is different and you won't be adding the same amount as the next guy will. your tank may also use alk more or less than another system, depending mostly on coral load.
2 and 3 part supplements are sold together, to solve this possible issue.
check out bulk reef supply. they have some interesting videos to explain the chemistry.

 

[Sebastian_Troy]

Is baking soda different to bicarbonate of soda?

 

[ccCapt]

Baking soda is sodium bicarbonate.
If you bake (in an oven) baking soda, it becomes sodium carbonate. Baking it drives out the co2.

If you use sodium bicarbonate (baking soda) to raise your alk, it will slightly lower your pH because of the co2 in it.
If you use sodium carbonate (baked baking soda) to raise your alk, it will slightly raise your pH.

 

[Sebastian_Troy]

Thanks ccCapt

Do you know how long I need to bake it for and how I can tell it is baked?

And does the pH come back up again once the co2 has dissolved out of the water?

 

[cmor1701d]

Bake on a cookie sheet for 1 hour at 350 or longer a/o hotter. That's the minimum. I did that yesterday to refill my alk doser. Also made up a gallon for my Calc doser.

Check out that linked article. Bulk Reef Supply has the chemicals for Ca and Mg. Baking Soda from the grocery (food grade) is all you need for Alk.

 

[ccCapt]

Thanks ccCapt

Do you know how long I need to bake it for and how I can tell it is baked?

And does the pH come back up again once the co2 has dissolved out of the water?

Cmor got you covered on the baking time. At least 1 hour at 350°.

The pH will rise or fall depending on what you use, but a I mentioned, it's not a big swing either way. It will return to it's previous level in a few hours.

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com
Sodium Carbonate - "Adding on the order of 0.5 meq/L of alkalinity increases the pH by about 0.3 pH units immediately upon its addition"
Sodium Bicarbonate - "Adding on the order of 0.5 meq/L of alkalinity drops the pH by about 0.04 pH units immediately upon its addition"

 

[kurtyboh]

there is a ton of great info on this thread!!!

 

[Tomchong22]

So I though chemistry in high school was boring and I would never really use it.....wrong lol. It's amazing how much stuff there really is to keeping fish and coral. Def following this for future reference.