pH and What is it really
submitted by T Hynes (Tanked Aquatics)
March 12, 2023

Everyone talks about it, but no one seems to know what it means, and yet, there on the shelf of every pet store there is a test kit for it. We test for it in swimming pools, hot tubs, aquariums and drinking water. So why are testing for pH? What is pH and what does it do for us, or the fish, or swimming pools and drinking water? I am not a chemist, however I have read enough to know about the fundamentals of pH to have become a dangerous informant.
First a little back ground. As a child under the age of 16, I made myself to be a pest of myself. I was the kid who would hang around for hours gazing at the fish, especially the small tetras to angel fish. The store was owned by a couple, who had for years invested their lives into their business. Expanding from just one store to six store in two states. I would go at every chance I had to look around that store. Leaving my mom to do the grocery shopping and heading over to the pet shop. One magical day that I can still remember with clarity, the manager at the time asked if I could fill in for her for three days while she went on vacation. I said absolutely, and from then on out in July of 1980 I worked at the store as an employee. I stayed working with the store through all of the changes of closing down all but one store, the market slowdowns, until the owner retired, and sold the store. I spent 17 years of my life there. I could go on about the time I spent there, the trials, the struggles, but that would get us off the task at hand here.

In discussing any subject it is really important that we all have a common frame of reference, because without one it would be impossible to discuss the subject. So fortunately or unfortunately we need to spend some time discussing basic chemistry.

So what is pH, “pH”, is an abbreviation for two words, Potential Hydrogen. So who cares? We care, because we can’t survive as a living entity without it. Biological metabolisms would not occur, medications could not exist without it. So to understand pH is also understanding the basic biological functions. So with that said lets open the door to the wonderful world of atoms.

Ever wonder how many atoms there are in a given substance? Can we even measure that? Sure we can. A gentleman by the name of Amedeo Avogadro (1776-1856) set out to come up with a standard definition of a mole. A mole is nothing more than a standard measurement of an element. You can read more about him and is work by just doing a little research yourself. But in basic terms he had defined the number of molecules in exactly 16 grams of Oxygen. The goal of the definition was to make the mass of a mole to be numerically equal to the mass of one molecule relative to the mass of hydrogen atom, and because of the law of definite proportions, this was the natural unit of the atomic mass.

In other words you can take any element off the period chart, measure one gram of that material and know that there are 6.022 x10^23 atoms with in that volume. As an example the element Gold, Au, on the periodic chart is numbered 79. Therefore 1 gram which equals 1 mole which contains 6.022×10^23 atoms with in that volume or mass. As I edit this, this morning the price of one gram of gold or now one mole of gold, it is worth $60.09. If you had 1kg = 2.2lbs, the value would be $60,088.35. Now let’s turn our attention to the periodic table. I know, yuck.

The elements on the periodic chart are numbered based on the atoms weight, Hydrogen itself as an element is number one on the periodic chart. Hydrogen is the first element on the chart because it is the lightest in weight. The next element is Helium. Next comes Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon, Sodium, and Magnesium. I could list the others but why?

The Periodic Chart is also divided into Metals, Gases, and Nobel Gases. This is why when you look at the chart it is arranged in the manner that it is. If you wish to learn more about the design of the chart and how it was created you can read about Dmitri Mendeleev Russian Chemist 1834 -1907, you can find him on YouTube as well.

Looking at the Periodic chart for Hydrogen there are numbers along with the symbol. Its Atomic number is 1, it has 1 proton, and has an atomic mass of 1.0079. Hydrogen however does not, if rarely exist on its own, it combines with another Hydrogen atom. So if you could get a hydrogen filled balloon, the gas inside would be H2 gas. As a molecule of hydrogen gas the molecular weight is 2.016. The molecule has two electrons and two protons.

Hydrogen mostly exists in the form of a gas all throughout the universe and on our planet. However under certain conditions it can be under immense temperatures and pressures that it is forced from a gas to a liquid metal. It is thought that both Jupiter and Saturn have metal cores of hydrogen. Hydrogen can also be an ice, but it has to be extremely cold. The temperatures are -434.45F or -259.14C. Interesting fact, for a star to form you need a large volume of Hydrogen that hovers at extremely cold temperatures. The cloud of Hydrogen needs to begin to collapse, it gains density as a result of gravity and given enough time will under the pressure start fusing the hydrogen gas into helium. That reaction generates electromagnetic radiation that we see in the form of light. Therefore if we had a gas bubble of hydrogen near our sun a star could not form because the temperature would not be conducive to such an event. This topic is better suited for Astrophysicists and Astronomers.

Atoms are made up of Protons, Neutrons and Electrons. Protons are particles that have a positive charge. Electrons are particles with a negative charge. Neutrons have no charge. Molecules are groupings of Atoms that have been bound together. Molecules bind together in three ways.

Ionic Bonding – this occurs when two atoms have opposite charges. For instance Chlorine has a positive charge, Sodium has a negative charge and therefore because of the electrical charge difference they come together to form what we know as table salt.

Covalent Bonding/Hydrogen bonding – this happens when two atoms end up sharing their electrons.

Metallic Bonding – this type of bonding between atoms occurs in metallic elements, and are formed by the valence electrons moving freely through the metal lattice

Before we go any deeper into the subject matter, there is one more concept that needs to be discussed; and that is the orbital shells of atoms. The orbital shell is the location of where the electrons orbit around the nucleus, and if you recall, the nucleus is made up Protons or Protons and Neutrons.
Let us start with Hydrogen atom.

A natural question arises from this.

If you could stand on an electron how far away would the Proton be?

If you were to scale up the proton to the same size of a basketball, then the electrons would orbit at a distance of 2 miles away. Therefore even on the atomic level distances are far. Atoms are mostly empty space. To put that into perspective imagine this next scenerio.

If you could take every atom that makes up the earth, the ground beneath your feet, remove all the space between the electron and protons and neutrons. The earth would be 184 meters in radius.

So its time to talk about the one thing that we are atempting to get to , and that is the one thing that aquariums need, water. We all know that water is the made up of 1 Oxygen atom and 2 Hydrogen atoms. Because of the unique way that these two elements combine to form water the molecule of water has a potential difference in its charge.

The Hydrogen bonds to the oxygen atom at a postion of about 4pm and 7pm reletive to the shape of the proton, and by doing so water become bipolar in its overal electrical charge.

Hydrogen only has 1 electron in its orbital shell and it wants 2, it is going to borrow 1 electron from the oxygen molecule to fill the orbital shell. And since there are two hydrogen atoms binding to the oxygen atom, another electron is borrowed from oxygen and as a result the Oxygen atom has an overall negative charge.

This is important because it will cause the water molcules to orient itself in such away to cancel out the electrical difference. See the image below.

Image Credit Tara A. Gross, USGS; Public Domain Usage

Now, what about water as a body of fluid

    Imagine a glass full of water that is 100% PURE water, with no minerals, no biological organisms, no viruses or bacteria, nothing but a glass container filled with 100% water. You would not just have molecules combined in H2O, but HO and H3O combinations as well. Most of the Hydrogen and Oxygen is going to be bound into the familiar H2O configuration. But what is left over and morphing inside that glass without you realizing that it is happening are molecules sharing electrons and atoms which changes the chemical makeup of the water

    You can’t witness it, but these configurations of atoms are constantly shifting back and forth. As a result you end up with different molecules forming between oxygen and hydrogen that have different charges, these are known as ions.

    What is an ion? An Ion is a charged atom or molecule. It is charged because the number of electrons are not equal to the number of protons in the atom. Hence the Hydrogen atom is an Ion. For an atom to be neutral the electrons must match the number of protons. I mentioned earlier about the NOBLE gases. Neon is one of those gases. What makes the atom noble you ask? Well let’s take a look at it.

    Neon is the tenth element on the periodic table. This means that neon has 10 protons, 10 Neutrons in its nucleus and 10 electrons. Remember the term orbital shell? The first orbital shell as I previously said can hold up to 2 electrons, however the 2nd orbital shell can hold up to 8 electrons. Neon does not need to borrow an electron from another atom, nor does it share its electrons, and therefore it does not bond to any atoms, it is stable, non-reactive. As a result it is considered noble. Now the question I hear is why does it glow? I am not going to go down that path, because that would take up another discussion.

    Now we can speak about pH measurements

To test pH we use a test kit based on some math. We don’t need to discuss the math involved, what we do need to know is what is the real difference between a pH of 6.0 to 7.0, and what is it that we are really measuring?

Disclaimer – the p in pH is debated. However Danish chemist Soren Peter Lauritz Sorensen in 1909, revised the pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells. Sorensen never explained what the p really stood for in pH, but his explanation of measuring pH was really using measuring the potential differences and that it represented negative power of 10 in the concentrations of hydrogen ions. So when I discuss the p in pH I use the term Potential of Hydrogen.
Measurement of pH is nothing more than a logarithmic scale. And for our purposes all one needs to know is that the difference between a pH of 6.0 to 7.0 or 8.0 is not just a factor of one, but it is a power difference of times more or ten times less depending on the reading of the test result. Therefore a pH of 5.0 is ten times more acidic then a pH of 6.0.

The pH of a fluid can have consequences to living organisms. Consider batter acid with a pH of 1, an accidental spill onto human skin would cause damage, but so would lye with a pH of 14. Not only do they cause damage, but the damage these substances cause are a result of different biological reactions. Battery acid dissolves the skin, whereas lye turns into a slippery substance, oil based and enters the skin.

Now here are some useless facts to fill your brain more with meaningless trivia unless you plan on going to medical school.

pH value of the human stomach is 1.5 to 3.5, pH Value of human skin 5.4 -5.9, pH value of human liver 6.99, pH value of the human brain 7.2

I have covered a lot of material here. The reason being is to give you the reader and myself a common frame of reference. In the next chapter of this saga we begin to discuss pH as it refers to your aquariums. What do we physically measure, how does pH help us and hurt us, what effects pH, should we be chasing pH, personal story of pH and a failure of someone misunderstanding pH which lead to death of many aquatic animals.
©2023- thhynes Tanked Aquatics for publication purposes general education SLC Aquatics