Sodium Carbonate vs Sodium Bicarbonate

[budsreef]

I have been using BRS Sodium Carbonate and was about to place an order when I noticed they also have Sodium Bicarbonate. Which is the right one to use in our tanks and why?

 

[ichthyoid]

<span style="font-size: 13px"><span style="font-size: 13px"><span style="font-family: Times New Roman">Sodium carbonate reacts with disolved CO2 and water (H2O) in your aquarium to form 2 Sodium Bicarbonates. This is represented by the equation below, where the Sodium Carbonate on the left, reacts with the CO2 and H2O to form sodium Bicarbonate on the right (plus a little heat, it's 'exothermic'). The Sodium Bicarbonate then acts as a buffer to hold your pH at 8.3. Think of it as a less expensive form/takes less to do the same job, and uses up a CO2 in the process. Does your brain hurt yet .</span></span>

</span><span style="font-family: Times New Roman"><span style="font-size: 13px"><span style="font-size: 13px">Na</span></span><span style="font-size: 11px"><span style="font-size: 11px">2</span></span><span style="font-size: 13px"><span style="font-size: 13px">CO</span></span><span style="font-size: 11px"><span style="font-size: 11px">3</span></span></span><span style="font-family: Times New Roman"><span style="font-size: 13px"><span style="font-size: 13px"> + CO</span></span><span style="font-size: 11px"><span style="font-size: 11px">2</span></span></span><span style="font-family: Times New Roman"><span style="font-size: 13px"><span style="font-size: 13px"> + H</span></span><span style="font-size: 11px"><span style="font-size: 11px">2</span></span><span style="font-size: 13px"><span style="font-size: 13px">O</span></span></span><span style="font-size: 13px"><span style="font-size: 13px"><span style="font-family: Times New Roman"> &gt;&gt; 2 NaHCO<span style="font-family: Times New Roman"><font size="1"><!-- gcu-updated --><font size="1"><!-- gcu-updated -->3</span></span></span></span>
</font><!-- gcu-updated SIZE --></font><!-- gcu-updated SIZE -->

 

[budsreef]

So you're saying use the sodium carbonate and not sodium bicarbonate?

 

[ichthyoid]

Budsreef;430199 wrote: So you're saying use the sodium carbonate and not sodium bicarbonate?

Yes, as long as it costs less than double the bicarbonate you come out ahead.

 

[ichthyoid]

Just curious, does your pH tend to run high or low? (any calcium reactor?) What you use may affect this.

 

[ichthyoid]

You may want to read this article by Randy Holmes-Farley. It is fairly technical, but well written and pretty comprehensive regarding pH in marine aquaria.

 

[budsreef]

I don't run a Calcium reactor and I haven't dosed for a while, I was waiting for my dosing pumps, so my PH runs a little on the low side, 7.91-8.06 over 24 hour period. It used to be a little lower without dosing until I switched salts from Reef Crystals to Seachem Reef.

I think the price was the same between sodium carbonate and sodium bicarbonate. I ordered the sodium carbonate.

ichthyoid;430222 wrote: Just curious, does your pH tend to run high or low? (any calcium reactor?) What you use may affect this.

 

[ichthyoid]

Thanks for the heads-up on the Seachem. I know a lot of folks like it, I have always used IO. The Sodium Carbonate will keep your pH up a little higher too, than the Bicarbonate will.

 

[ichthyoid]

ares;430275 wrote: if I use baking soda, my PH hits the floor, if I cook the baking soda first, it goes up.

thats all I know. and I cook mine. I find about 10min at 450 is apparently a good mix, leads to my PH being relatively unchanged and my alk rising as I want.

That's exactly right/the way it works, although 'hitting the floor' may indicate other problems. Cooking the Sodium Bicarbonate is called 'calcining' and converts it into Sodium Carbonate by driving off CO2 and water. So, in effect you are using the same thing. The reason the Carbonate raises pH is because it 'consumes' one CO2 molecule for every melecule of Sodium Carbonate when converting to the Bicarbonate in the aquarium. CO2 in solution forms Carbonic Acid, so when you decrease that pH goes up.

 

[ichthyoid]

ares;430275 wrote: if I use baking soda, my PH hits the floor, if I cook the baking soda first, it goes up.

thats all I know. and I cook mine. I find about 10min at 450 is apparently a good mix, leads to my PH being relatively unchanged and my alk rising as I want.

To quote Randy Holmes-Farley on this (using Bicarbonate), below is his article on dosing 2 part...

Recipe #2 is for use in reef aquaria whose pH is on the high side (above 8.3 or so). It will have a very small pH lowering effect when initially added. The pH drop achieved will depend on the aquarium's alkalinity and, of course, on how much is added. Adding on the order of 0.5 meq/L of alkalinity drops the pH by about 0.04 pH units immediately upon its addition.

 

[weaglereefer]

Dang, guess I should have ordered the Sodium Carbonate. My pH runs around 7.9, and I'd like it a tad higher.

 

[ichthyoid]

au01st;430287 wrote: Dang, guess I should have ordered the Sodium Carbonate. My pH runs around 7.9, and I'd like it a tad higher.

Or, you can just spread Sodium Bicarbonate on a clean cookie sheet and cook it at 450 deg for an hour in an oven. This will drive off CO2 and water, thus converting it to Sodium Carbonate. The process is well known to Chemists and Chemical Engineers and is called 'calcining'. You should notice it is more soluble, and raises the pH.

 

[weaglereefer]

So I'm going to bake it to drive out the water then mix it with water, lol.


Spent last night figuring out how much Ca additive to add so dosing is easy for all 3 tanks. I've set it up so 1tsp is 10ppm in my 10g, the rest just fall in line. 2.5tsp is 10ppm in my Aquapod and 10tsp is 10ppm in my 90 (adjusting for sump, fuge, and rock). Hopefully the 90 won't need much adjusting with the kalk reactor running.

 

[ichthyoid]

Yup, cook off the water AND CO2. It's the CO2 that's important in this process.

 

[james s_]

Sodium Bicarbonate is good for making large changes in Alkalinity without effecting PH. The videos BRS has are pretty informative...they helped me quite a bit while deciding what to order....

 

[budsreef]

Good point James, I didn't think to look at the videos. Their written description was the same for both products. Luckily, I went with the sodium carbonate since I got it in the 5 gallon size. Unfortunately, they were out of the 5 gallon Calcium or I would have gotten it as well since it was such a great price.

James S.;430386 wrote: Sodium Bicarbonate is good for making large changes in Alkalinity without effecting PH. The videos BRS has are pretty informative...they helped me quite a bit while deciding what to order....