Mixing NaHCO3 with tankwater

[kae]

Can I mix baking soda with tankwater instead of freshwater? For example, 1 litre of tankwater with 4 tsp. of baking soda. Thank you.

[bertoni]

The baking soda should dissolve, but the alkalinity might climb high enough to cause precipitation. 4 tsp sounds like a lot for a liter of water. Any baking soda that doesn't dissolve might end up landing on an animal and irritating or damaging it.

[kae]

Thanks for fast reply bertoni.

Is it possible that pH of the mixture will be low enough to prevent precipitation?

Thank you.

[bertoni]

I doubt that very much. Baking soda has only a small effect on pH. You could try it, though.

[MCsaxmaster]

That will raise the saturation state of CaCO3 very, very high (up near 95 for aragonite--compare that to about 3.5 - 4.5 in sea water, and usually not over ~6 in tank water). It is very feasible to precipitate CaCO3, but precipitation is limited by kinetic processes (happens slowly). As long as you mix it up and dump it in you'll probably be fine. I've done this many times and never noticed any precipitation, but I was dumping it right in the tank.

cj

[kae]

Originally posted by MCsaxmaster
It is very feasible to precipitate CaCO3, but precipitation is limited by kinetic processes (happens slowly).

What is the reason behind that, pH or what? Thank you.

[Boomer]

It is a function of pH, Alk and Ca++

Randy talks about it here called Omega values. Look 1 /3 of the way down the page and you will see the Greek Omega symbol/letter.

http://reefkeeping.com/issues/2002-0...ture/index.htm

Omega = 1 (risky: dissolution of aragonite begins here)

So what Chris is saying is that you will drive up the Alk and pH and get an Omega value that is in the range of 6

Omega= 6 (non-biological precipitation is more likely)


Like
pH = 8.2
Calcium = 410 ppm
Alkalinity = 5.0 meq/L

or more like

pH = 8.0
Calcium = 410 ppm
Alkalinity = 8.0 meq/L

= Snow storm or precip

[MCsaxmaster]

Originally posted by kae
What is the reason behind that, pH or what? Thank you.

What is the reason behind what? Are you referring to precipitation or the rate?

cj

[kae]

Originally posted by MCsaxmaster
What is the reason behind what? Are you referring to precipitation or the rate?

cj

I referred to the reason why precipitation happens slowly in spite of alkalinity is very high. Thank you very much.

[MCsaxmaster]

Precipitation happens slowly because, well, it just tends to happen slowly. CaCO3 doesn't precipitate terribly quickly, no matter what we do to the chemistry (though the higher the superstaturation, the faster it tends to happen).

cj