waterdrop
Enthusiastic "Re-Beginner"
You'll probably remember from high school chemistry (what's the UK name for high school?) that the pH scale is just trying to measure free protons (thus the term p for protons and H for Hydrogen (Hydrogen the element is just a single proton with its one electron buzzing around it in a round shell (Hydrogen the gas is H2.)) So whenever something steals away that one electron with its minus charge, a proton with a plus charge is left. The more plus-protons, the more acid. (some high school chem teacher will probably correct me 
)
So most of us get that lots of plus charges being available is associated with acidity and a lack of that exists at the other end of the pH scale but we don't often think about the systems that needed to occur in nature (for living things like plants and animals) to have a ready system to *resist* extreme occurances of acidity and its opposite.. since those extremes are very reactive and would likely involve destruction of cells and tissues!
These systems that resist extreme changes are called "buffering systems" and are extremely important to plants and animals. We humans, for instance, have elaborate systems of water, CO2, carbonic acid/bicarbonate and hydrogen ions to protect our nervous system tissues, which are easily destroyed if pH gets out of control and things get too reactive. Likewise, for living things that live in freshwwater aquatic environments, the surrounding water and its natural cycles have buffering as one of the things going on and playing a big role in the chemistry of the animals and plants sometimes.
OK, so that was my attempt at a "big picture." Back down to the pH in our "bacterial growing soup," right? We know that our particular two species grow best at pH 8.0 to 8.4 and we know that as we fishless cycle, they are processing the packaging of the Nitrogen from NH3 to NO2 to NO3, right? Well, the problem comes when that NO3 is dissolved in water. Like many substances, it doesn't just float around in that nice NO3 package, it's little electrons are busy flying around being attracted and repulsed by other surrounding charges, right? So the N is the big Plus and at any given moment 2 of the O's have the negative and the third O is double-bonded to the N and is more neutral. But in water it gets trickier than that because there will be some protons (H+) out there and a little bit of our NO3- (NO3- is what nitrate is) (about 7% of our nitrate ions) will grab protons and form HNO3 which is one of the strongest acids known.. Nitric Acid! Whoa!
Well, it turns out that the bicarbonate (that we can get by tossing in that baking soda and letting some of the little sodium ions separate so we get bicarbonate (HCO3-) is the perfect "buffer" for nitric acid (HNO3, which dissociates in solution, easily letting those super acid H+ protons go free, which is why its such a strong acid).. anyway its perfect because its not only a negative ion, ready to latch on to those protons, but also apparently because it, bicarbonate, is "isoelectronic" with nitric acid. The theory (I don't really understand it but its out there) is that as molecules are of similar size and shape and share electron shells that are positioned to react particularly well together. So, the bicarbs hug the protons the nitric acid has let loose and soak up the acidity, make sense?
Gee, I've forgotten the aquarium part of this discussion Where were we? Well, baking soda is perfect because we have a lot of control over its dosing, we can see feedback with our pH tests and re-adjust and it all "goes out with the bathwater" so to speak when we do the big water change at the end of fishless cycling and we don't have to worry about too much of it's sodium or whatever being around to bother our fish. Once fishless cycling is over we want the mineral content of our tap water to buffer the system for us and usually it does because we won't be running the nitrogen cycle at ramped up speed and thus we won't be producing nearly as much nitric acid.
My rule of thumb about bicarb dosing is that 1 teaspoon per 50L only changes KH, not pH and 3 teaspoons per 50L changes pH a whole lot, so 2 teaspoons per 50L is the sweet spot where you can get a handle on what the baking soda is going to do in your particular tank that is fishless cycling. Any buffer like baking soda is going to act directly on KH (carbonate hardness) (the other members will explain this further) but indirectly on pH. If you are interested in water chemistry, its interesting to have a GH/KH set of kits but its not necessary if you just want to grow the bacteria, you can just watch pH for changes.
~~waterdrop~~
(sorry I probably didn't answer the practical question.. let me know and I can probably do that fish tanks are just an excuse for the real fun, science and the world, lol)
)So most of us get that lots of plus charges being available is associated with acidity and a lack of that exists at the other end of the pH scale but we don't often think about the systems that needed to occur in nature (for living things like plants and animals) to have a ready system to *resist* extreme occurances of acidity and its opposite.. since those extremes are very reactive and would likely involve destruction of cells and tissues!
These systems that resist extreme changes are called "buffering systems" and are extremely important to plants and animals. We humans, for instance, have elaborate systems of water, CO2, carbonic acid/bicarbonate and hydrogen ions to protect our nervous system tissues, which are easily destroyed if pH gets out of control and things get too reactive. Likewise, for living things that live in freshwwater aquatic environments, the surrounding water and its natural cycles have buffering as one of the things going on and playing a big role in the chemistry of the animals and plants sometimes.
OK, so that was my attempt at a "big picture." Back down to the pH in our "bacterial growing soup," right? We know that our particular two species grow best at pH 8.0 to 8.4 and we know that as we fishless cycle, they are processing the packaging of the Nitrogen from NH3 to NO2 to NO3, right? Well, the problem comes when that NO3 is dissolved in water. Like many substances, it doesn't just float around in that nice NO3 package, it's little electrons are busy flying around being attracted and repulsed by other surrounding charges, right? So the N is the big Plus and at any given moment 2 of the O's have the negative and the third O is double-bonded to the N and is more neutral. But in water it gets trickier than that because there will be some protons (H+) out there and a little bit of our NO3- (NO3- is what nitrate is) (about 7% of our nitrate ions) will grab protons and form HNO3 which is one of the strongest acids known.. Nitric Acid! Whoa!
Well, it turns out that the bicarbonate (that we can get by tossing in that baking soda and letting some of the little sodium ions separate so we get bicarbonate (HCO3-) is the perfect "buffer" for nitric acid (HNO3, which dissociates in solution, easily letting those super acid H+ protons go free, which is why its such a strong acid).. anyway its perfect because its not only a negative ion, ready to latch on to those protons, but also apparently because it, bicarbonate, is "isoelectronic" with nitric acid. The theory (I don't really understand it but its out there) is that as molecules are of similar size and shape and share electron shells that are positioned to react particularly well together. So, the bicarbs hug the protons the nitric acid has let loose and soak up the acidity, make sense?
Gee, I've forgotten the aquarium part of this discussion
Where were we? Well, baking soda is perfect because we have a lot of control over its dosing, we can see feedback with our pH tests and re-adjust and it all "goes out with the bathwater" so to speak when we do the big water change at the end of fishless cycling and we don't have to worry about too much of it's sodium or whatever being around to bother our fish. Once fishless cycling is over we want the mineral content of our tap water to buffer the system for us and usually it does because we won't be running the nitrogen cycle at ramped up speed and thus we won't be producing nearly as much nitric acid.My rule of thumb about bicarb dosing is that 1 teaspoon per 50L only changes KH, not pH and 3 teaspoons per 50L changes pH a whole lot, so 2 teaspoons per 50L is the sweet spot where you can get a handle on what the baking soda is going to do in your particular tank that is fishless cycling. Any buffer like baking soda is going to act directly on KH (carbonate hardness) (the other members will explain this further) but indirectly on pH. If you are interested in water chemistry, its interesting to have a GH/KH set of kits but its not necessary if you just want to grow the bacteria, you can just watch pH for changes.
~~waterdrop~~
(sorry I probably didn't answer the practical question.. let me know and I can probably do that
fish tanks are just an excuse for the real fun, science and the world, lol)
things are moving now Lee
