GH, KH, and pH for the Advanced Hobbyist

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Hér er mjög góð grein sem ætti að svara flestum spurningum um efnafræði vatns í fiskabúrum. Greinin er á ensku og ég þurfti að lesa nokkrum sinnum yfir sumt til að ná því almennilega inn.


GH, KH, and pH for the Advanced Hobbyist

by Bob Dixon

When reading internet discussions about keeping South American and West African biotope fish, it seems there is always a "newbie" with a problem that sounds something like this:

"I added pH Down to reduce my pH to 5.5, but then my KH dropped to 2.0. I added calcium carbonate to bring my KH back up to 6, but then my pH went back up to 8.0. I bought some Discus Buffer, and followed the directions. This lowered my pH to 6.0, but more pH Down couldn't get it any lower. Then I found that my KH was back down to 2.5, so my friend said to add some baking powder, and this brought my KH back to..."

By the time you get to the end of this poor fellow's posting, he can't ~ a net through the water Cast enough to catch the snails, because the water bas turned to jelly. He has $172.00 worth of chemicals in a 5-gallon tank, and his fish have applied for Federal Toxic Waste-Site Cleanup Funding!

He still doesn't have the water parameters he wants, because in truth be is totally clueless about what the parameters are all about. The breeder he gets his fish from tells him they need a low pH. The store clerk, who doesn't even know what Pelvicachromis taeniatus looks like, tells him it will "acid crash" if the KH gets below a certain point. His next door neighbor, who keeps a saltwater reef tank. is advising him about all kinds of stuff. that simply does not apply to freshwater. This is supposed to be fun. This is supposed to be easy. This is not supposed to cost two weeks wages every seven days just for chemicals.

To avoid the above scenario I have written the following article. I hope that by reading it, you are able to enjoy your hobby more.

There are five basic water parameters that play a part in establishing the necessary water for our fish to be happy and thrive.

Temperature
PH
Hardness
Alkalinity
Conductivity

Notice I am not listing ammonia, nitrates, or nitrites, Those are not issues of water parameters, except perhaps for folks working with aquatic plants. From a fish keeper’s point of view, ammonia, nitrates, and nitrites are an issue of water quality, not water parameters.

So let me say this now, and I won't have to say it again. Do your regular, scheduled partial water changes. Keep the levels of nitrogen waste and dissolved organic compounds down. "How do I do this", you ask? By doing regular, scheduled partial water changes. Oh, and did I mention doing regular, scheduled, partial water changes?

Temperature:

I shan't bother to discuss temperature here either. That is a fairly easy thing to achieve. Most of us understand how to read a thermometer. I will mention before moving onto the good stuff that one should check all of their thermometers periodically . At the very least stick your finger in the tank at least once a week. Heaters seem to be self-adjusting, so keep an eye on them. The other four parameters are chemical in nature, and as such. are inter-related in ways we tend to forget at times. Follow these simple, easy to remember rules and you will not become like the poor chap in the beginning of this article.

We cannot understand these four inter-related parameters without a brief discussion of the general laws of nature of certain elements and compounds. These laws are described in layman's terms as The General Laws of the Nature of Elements and Compounds. As I am not a chemist, I will do my best to be accurate and correct, and still keep it comprehensible for the rest of you. Let's see how well do:

All chemicals which are not in a pure "elemental” state are compounds, made up of two or more elements. These compounds are held together by either ionic or covalent bonds. The differences lie in the nature of these chemical reactions.

All elements are made up of atoms, which in turn have varying numbers of protons and neutrons, depending on the particular element in question. Which element a given atom is, can be determined by counting the number of protons in its "nucleus", or central core. Of course, this would require a really big. powerful microscope. For practical purposes, we generally handle the atoms as a bunch and determine what they are by their physical properties.

Each atom also has one electron for each proton. These electrons are attracted to the protons by possessing an electrical charge, which is opposite in polarity to that of protons. It is also the movement of these electrons through a wire from atom to atom that we call "electricity". This attraction doesn't keep them in place. but rather they cruise around the nucleus of the atom in a sort of orbit.

The orbit is not a circular path, like the orbit of a planet around the sun. Instead, they sort of buzz around like groupies around a rock star's stretch limousine.

These electrons for all their wandering ways, are actually rather well organized little dudes. They like to form up in layered groups, referred to by physicists interchangeably as “rings" or "shells". The outermost shell is referred to as the “valence shell". This is where all the chemical reactions that keep the world interesting take place.

Hydrogen has only one proton and one electron, while Helium has two of each. Helium does not react chemically because these two electrons are happy as a pair. They just hang out together, and don't want any company, nor are they prone to wandering off. These two elements form the outermost or valence shell (actually the only shell), and because they are happy and cozy together, they consider that “shell" to be complete.

But Hydrogen's single electron is very lonely, and misses the company of other like-minded, sub-atomic particles. So it is always willing to either run off somewhere in search of friends, or lacking that opportunity, is open to having company over. Only one guest at a time, mind you, but company nevertheless. When the electron has escaped the confines of home, it leaves the Hydrogen atom with an unmatched, positive electric charge, and this atom is considered an "ion", or .”cation"- a positive ion at that. When the electron has a visitor, they form a complete valence shell, possessing an extra negative electrical charge. This causes the Hydrogen atom to be an "anion". Unlike “positive” and "negative" people, this does not reflect upon the atom's state of mind, only its electrical state of being.

"Mother Nature" prefers her atoms to remain balanced. Electrical charges, being such as they are, a positive Hydrogen ion will find a negative ion, and the two will stick together like magnets, flying around in the air like two Florida love-bug. This is the natural state of Hydrogen gas. It always exists in a "diatomic" or two-atom state. The electron's buzz back and forth from one atom's valence shell to the others and is called "Conning a covalent bond".

Lithium, which has three protons has a third associated electron, compelling it by the other two to a lonely existence in a second shell. The first two still consider themselves complete. But the Good Lord in his wisdom has decreed that electrons in all the shells outside the first will not be complete until there are eight of them. This compels the third electron to roam if it wants to find companionship, and causes Lithium to become a positive cation.

Beryllium, the next element, has two of these lonely heart electrons and so it goes. Chlorine and Fluorine have seven electrons in their valence shell. Oxygen and Sulfur have six. and are busy looking to fill its vacancy. When all electron or two from one atom move in with electrons from another, the electrical charges of the two resulting ions draw them together forming what is called a "compound molecule". Sometimes the atoms will connect up and share the electrons. They will then form a covalent bond. When the electrons from one atom stay in orbit around the other atom, this electric attraction is called an "ionic" bond. Ionic bonds are not very strong and are fairly easy to break when in the presence of an ionic solvent such as water. This is where we as aquarists come in.

PH:

This is often the first parameter we learn about when we get into the hobby, and sadly it is the least understood. Take this simple quiz and see how you do.

1) What does the abbreviation pH stand for?

2) How much more acidic is water with pH of 4.5 than water with a PH of 5.5?

See? We don't understand much about pH after all. The answers are "per Hydrion" and "ten times" respectively. Allow me to explain.

Hydrogen in its cation state is known as "hydrion". The pH scale is a logarithmic scale and can also be referred to as a "molar concentration" of hydrion ions. Now you are scratching your head and saying "Huh"? A "mole" in chemical terms is a set quantity of molecules, that quantity being referred to as Avagadro's number. Consider the number 602 with twenty-one zero's trailing it. That's a mole. A "molar concentration" is the number of moles of hydrion ions in a liter of water. Since it works out to be less than one, we can express it as a fraction (groans from the mathematically challenged). When you see a pH value of "X", it really means the molar concentration is 1/10x moles of hydrion for each liter of water. So, if you have a pH of 5.0 that means that for each mole of stuff in the sample you have 1/105, or 0.00001 moles of hydrion. Doesn't sound like a lot, but remember a mole is a really big number. You would think that it contains a lot of hydrion, but it doesn't. One mole or 602,000,000,000,000,000,000,000 ions of hydrion works out to weigh only one gram, That means a liter of water at a pH of 5.0 has only ten micrograms or ten millionths of a gram of hydrion ions. A pH of 6.0 indicates a concentration of 0.000001, or one millionth of a gram.

What about a pH of 5.1 you ask? Or 5.2, 5.3, etc? Remember this is a logarithmic scale so it kind of curves its way along, with the difference between 5.0 and 5.1 being greater than the difference between 5.1 and 5.2, and so on. Suffice it to say that it is somewhere in between and the closer it gets to6.0, the fewer it has.

At this point I would like to introduce a scientific convention. Scientific conventions are things scientists all agree on so they can communicate better (and I' " bet you thought it was a bunch of nerds with lab coats and pocket protectors taking over a hotel). When a Hydrogen atom is in the hydrion state it can be shown as "H+". When it has an extra ion and therefore is negatively charged it is written as "H-" and is called Hydride. The chemical symbol for Calcium is Ca and when it is in ionic form it will be short two electrons. This will cause it to have a double positive charge and will be written as CA++. Nifty huh?

I would also like to take a minute here to discuss "mass solutions.. as opposed to "molar solutions". While molar solutions are based on the number of molecules of something in one liter of water, a mass solution measures the weight of the substance dissolved in a liter of water. It is expressed as mg/1 (milligrams per liter) or mmg (micrograms per liter). We will need this definition later so stick it into the back of your head for future reference.

We are now ready to discuss the idea that water below a pH of less than 7.0 is "acidic" and above 7.0 is considered ..base". If you were to distill water to an absolute purity and keep it from dissolving anything - even air, it would have a pH of 7.0. Why? Because water is an ionic compound. As such its chemical bond is not as strong as it would appear.

In truth some of it breaks down into hydrion or "H+", and hydroxide or "OH-". Enough of it so that you have 1/107 ions of each. Which gets us to the point of "pOH" or "per Hydroxide". The "pOH" measures the quantity of "OH."- ions swimming around independently of each other bumping into each other and also bumping into water molecules. These ions don't stay separated, and will reform into water, while some of the water molecules break down into ions again.

This constant forming of ions and water molecules is controlled by the forces within the ions and establishes a thing the chemically enabled call "equilibrium". Unless acted upon by some outside influence, there will always be 1/107 (0.0000001) moles of both hydrion and hydroxide per liter of water. At this point it is quite obvious that you have a pH of 7.0 and not quite so obvious that you have a pOH of 7.0. Relevant to the imminent discussion is the fact that the pH plus the pOH equals 14.0. Read on and see.

So one might wonder what kind of outside influences might upset this wonderful equilibrium. I know I certainly did. And here is what I found out.

Suppose you introduce some Hydrogen Sulfide (in the Queen’s English it is Hydrogen Sulphide - that’s why spelling bee champs are always Americans). If you look back toward the beginning of this discussion you will recall that Sulfur has only six electrons in its valence shell seeking two electrons to fill its shell. Since each Hydrogen atom has only one, it takes two Hydrogen atoms to sate Sulfur’s appetite. Hydrogen Sulfide is written as "H2S” indicating two atoms and one Sulfur atom. So what happens to this wonderful '.H2S” when it is dumped into water? Since it is another ionic compound, it breaks up into one S- ion and two H+ ions. This increases the number of H+ ions by doing their little s1am-dance in the water. This in turn increases the number of incidents where H+ and OH- ions find each other and combine to become water.

Since there are more H+ ions than OH- ions~ we end up with some extra left over. This causes the equilibrium to shift resulting in enough H+ ions and OH- ions that the two logarithmic values will equal 14. So, if you have a pH of 6.0 or 1/106 (0.000001) moles per liter of H+ ions, you will now have 1/108 (0.00000001) moles per liter of OH- ions, assuring that pH + pOH = 14.

The Hydrogen Sulfide solution known as "sulfurous acid~' can be quite nasty when the pH gets low enough. If we decided to return the balance, we could introduce something with lots of OH- ions like Calcium Hydroxide (CaOH2). Just the right amount would offset the extra H+ ions and return it to a pH of 7.0 and a pOH of 7.0. Too much and the equilibrium swings the other way.

The higher the pH- the lower the pOH, and the less hydrion you have- the more hydroxide you have. This high hydroxide condition is called "basic" water. The lower the pH, the higher the pOH, the more hydrion you have- the less hydroxide. This is called "acidic”. water. The more acidic or the more basic the water becomes, the more of these ions you have actively, even aggressively. They search for new ions to attach themselves to in order to find the atomic bliss they desire. This is why acids will dissolve metal and bases. When they get strong enough they actually attack even the glass that your aquarium is made of.. Not for us to worry, though. We keep acidic water fish.

Now that you know more about pH than you thought was humanly possible, we will move on. As we discuss the other parameters, we will discover the relationships they have with one another.

Hardness:
We use the abbreviation "GH" when discussing hardness. GH actually stands for General Hardness. That's informative, but what is hardness? There are two stories about how the tern "hardness" came about. One relates to the idea that when water is "hard", it is hard to get soap to lather; This is true, hard water does make it hard to get a good head of suds on your bar. But then I would expect the opposite of hard water to be "easy" water. Instead it is called "Soft" water, and this lends some credence to the second story. In this tale, railroaders and others that worked around boilers, noticed that some water left a hard coating on the inside of the boiler, while some water left a comparatively soft coating, even virtually no coating at all.

Scientists both in the United States and Germany began studying this phenomenon, and discovered that hard water contained a lot of ionic chemicals with cations of a +2 valence. We mentioned earlier that Beryllium (Be) and Calcium (Ca) have a valence of +2. So do Magnesium (Mg), Strontium (Sr), Barium (Ba),and Radium (Ra). On occasion, Iron can also have a valence of +2. I hesitate to show you the scientific notation for Iron, for it is (Fe). Not I, Ir, or even 1o. Perhaps it was thought up at one of those scientific conventions, the kind with the lab coats at the Holiday Inn. Anyway, scientists in different countries came up with a scale for measuring the hardness of water. In the United States, we use GH, or General Hardness. In Germany (they call their country Deutschland), they use the term DH, or Deutch Hardness. Since a lot of the fine aquarium equipment we use are made in Germany, we sometimes find test kits that measure DH instead of GH. These two scales are somewhat different but not significantly. They both are somewhere between 17 parts per million and 18 parts per million. That means the difference is not significant to anyone that doesn't wear a lab coat and a pocket protector.

But wait what is this “parts per million"? Another scientific convention determined that mg/l was not useful for dissolving things in alcohol, oil, or even air. So they came up with "parts per million"- abbreviated as "ppm". One part per million means that for every one million grams of solution, one gram of it is the “solute" or the thing being dissolved. The thing doing the dissolving (in our case water), then, must also have a scientific name, and so we call that stuff the "solvent". This holds true whether we are measuring in grams, pounds, ounces, stones, or any other weight standard one can find still in use around the world.

So how do we relate the mass solution of "ppm" to the mass solution of mg/l? Fortunately for us, we are using water as a solvent. When scientists decided to invent a new, scientifically based, universal standard for measuring, they came up with the metric system. First they established a measure of length, as determined by the distance between two specific places on Earth, in order to always, have a reliable standard to check from. I don't remember what these two places were, but it doesn't matter anyway, because as it turned out, they measured the distance wrong, and didn't discover it until they had decided how long the standard of length would be.

Undaunted by this initial inaccuracy, they also decided to establish a standard for measuring weight and volume based on this new unit of 1ength, called a "meter". They found that if they took a length of one one-hundredth (1 /100) of a meter, hereinafter known as a "centimeter" (centi being borrowed from the Latin for one-hundred), and made a cube of it, then one thousand of these little cubes would add up to something close to a quart.. So they called one thousand cubic centimeters a "liter". That makes one cubic centimeter a 'milliliter", because milli comes from the Latin for thousand. We can abbreviate all these terms as “cm”, for centimeter, "1" for liter, and "ml" for milliliter. So how does all this help when working with ppm and mg/l in water. Well, they also figured out that one liter of water was a little over two pounds. Looking to get a unit smal1er than ounce, they decided that the two pounds found in one liter of water would be cal1ed a "kilogram", from the Greek for "thousand weights". Additionally, one ml also known as one cc, is the same as one gram. { note to self: These scientists really dig Latin and Greek terms for things. I should research to see if the white lab coat is derived from the white toga} . One mil1igram or mg is one thousandth of a cc, making it one millionth of a liter, as long as we are talking about water. So, for solutions of water, one ppm and one mg/l are the same.

The more stuff you dissolve in a liter of water, the more it weighs. Our straight conversion begins to lose some accuracy as the amount of stuff in it increases. Nevertheless, for us as hobbyists, this discrepancy will never get big enough in a fresh-water tank to bother our fish. We shouldn't let it bother us either. For our discussion here, consider ppm and mg/l to be synonymous when discussing freshwater aquaria.

Back to our discussion on hardness. Scientists established a standard of “Degrees of Hardness". They figured out through the scientific method (also a topic for future discussion) that there was hardly any Be, Sr, or Ba in most naturally occurring water supplies and certainly no Ra (which might make water glow in the dark). The majority of it was Ca, with a lesser amount of it being Mg, and trace amounts of other things. Scientists then developed test kits that involve dropping a liquid in a sample of water until the liquid changed color, while counting the drops. Since they couldn't agree on whether to use DH or GH, some test kit manufacturers came up with test kits that measure in ppm.

But there was and still is a problem with these tests. Since all these ions that the test kits measure have a valence of 2+, they all reacted the same on the molar concentration. Unfortunately, we are working with mass concentration. To solve this problem, the test kit manufacturers have calibrated their tests to read as though all the ions are Ca. When you use a test kit or get a water quality report from your local water authority, it will give you the hardness in ppm or mg/l as Ca, or worse yet as caCO3 (calcium carbonate).

In order to determine the actual weight of each of the various +2 ions in the solution, you have to first measure with another kit to determine how much is Ca. Then subtract from the total, converting what's left by looking up the “atomic" weight of each of these things on a periodic table,. then do a bunch of math.

Fortunately for us, our fish don't seem to care which +2 ions they are, only that they are there. So if we treat it alias Ca++, we will be fine. This simplifies it tremendously.

Alkalinity:

Alkalinity by definition refers to a given body of water's ability to resist becoming more acid. Within the aquarium and pond hobby it is also known as buffering capacity, pH stability, or carbonate hardness. What it means for hobbyists trying to keep soft water rainforest fish is lot of headaches.

I'm confident that almost all of us has added some sort of pH-reducing agent to a tank, only to have that tank go through a "bounce-back". You know what bounce-back is don't you? That's where you have water out of the tap at a pH of perhaps 7.8. You add enough pH-reducer to bring it down to 6.0. and go to bed happy. knowing that tomorrow your tank will be ready to hold that special pair of apisto’s. Yet, when you wake up the following morning your tank mysteriously returned to 7.6, or maybe even all the way back to 7.8. You add more stuff, get the pH back to where you want it and make the five hour trek to pick up the little darlings. When you return. guess what? Yep. Right back in your face- pH of 7.4.

So what's going on here? Alkalinity. Alkalinity is based on a chemical reaction between hydrion and a buffer. Remember what makes water acidic and basic? The relative number soft H+ and OH- ions. If you have more H+ ions. then your water is acid. The more H+ you have, the more acidic it becomes. Take away some H+ ions. and it becomes more basic.

But what is this "buffer', and how did it get in my tank? I certainly didn't put it there.

Yes. I’m afraid you did. It was in the water when it came out of the faucet, and in the bucket that you carried to the fish room and used to fill the tank. Remember earlier when we talked about hardness and +2 ions? And even before that we talked about Mother Nature liking balance. Well, this is that balance. For every cation charge in the water there is an anion charge. To say there is an anion for every cation would be careless, for it is the charges themselves that must balance.

We have already briefly mentioned Hydrogen Sulfide and that each molecule of the stuff has one S- ion and two H+ ions. The two + charges are needed to offset the single atom with the -2 charge. One anion but two cations. Some of these anions are very quick to react with hydrion, and to eliminate it from the equilibrium between hydrion and hydrate ions. These fast-acting anions are called buffers.

Let's explore a little further the relationship between anions and cations. We will imagine a one liter tank of pure distilled water. Into it we will add one mole of Calcium Chloride (CaC12). Then let us add one mole of Sodium Nitrate (Na2NO3). So what we think we have is a mole solution of CaC12 and a mole solution of Na2NO3. What we have in a practical sense is a six mole solution of ions. One mole is Ca, two moles are CI, two moles are Na, and one mole is NO3. Note that the last- the nitrate, is itself kind of like a compound. as it is composed of one Nitrogen ion and three Oxygen ions. In most chemical reactions, it acts like a single atom. This is because the bond is more covalent than ionic. with the valence electrons doing a sort of swing around the entire molecule, rather than just one or two atoms.

It can be said that the Calcium and the Chloride are "associated” with one another, because they have an affinity for one another. If you let the water evaporate out the resulting crud in the bottom of the tank would be a mix of Calcium Chloride, Calcium Nitrate. Sodium Chloride, and Sodium Nitrate. There are rules of electronegativity that we need not learn in this discussion. which would determine the actual ratios of the four salts to one another.

In a typical glass of water from a household faucet, we have a sort of ion soup. In some places that soup is very dilute, more of a consume than a soup. In other places that soup is very thick, kind of like a stew, or maybe a chowder if you prefer. Cations and anions swim around in a free-for-all, bouncing into each other, slam-dancing in the water.

When certain ions bump into each other, a chemical reaction takes place. This has to do with electronegativity, which would take about half of a ninth-grade science book to explain adequately. Basically, it means that certain ions react more willingly than others, and certain ones have preferences for other certain ones.

An example of a Calcium compound dissolved in water is Hydrofloric Acid. Hydrofloric Acid is a particularly nasty thing and extremely reactive. In fact it will even eat through glass, which makes it hard to carry around. If anyone offers you some walk away. It is very, very dangerous stuff!

But assuming we were foolish enough to mess with it, adding HF to any water containing Calcium ions will result in the formation of CaF2. The vast majority of this will "precipitate out", which means it will form a solid substance and sink to the bottom. The M+ ion that is left will then associate with whatever anion the Calcium was originally associated with.

We are now ready for a discussion of the buffer that i sin your water. I mentioned that Nitrate is an anion made of a number of atoms, like a compound. A lot of anions are in fact multiple-atom affairs. Along with Nitrate there is Phosphate, Silicate, Nitrite, and Borate to name a few. The ones that we are most interested in when dealing with alkalinity is carbonate (CO3-).

Carbonate is a very unstable ion. It seems to have an intense desire to hook up with hydrions. When it is swimming around in its ion soup, it bumps into H+ ions, along with any other ions out there. When it bumps into H+ often enough. it attracts and holds these ions for just a tiny fraction of a second. If it ends up with two of them at the same time it forms M2CO3, which is called Carbonic Acid. The Carbonate Acid then falls apart, but not back into its original: ions. The two M+ ions will talk one of the three 0- ions into deserting and forming a new molecule of its own. These atoms form a relatively more stable H20 molecule and leave the other three to become CO2. Well, hey, if that isn't Carbon Dioxide another fairly stable molecule. The unstable carbonate and the highly unstable hydrion have both found something they like better.

Unfortunately, this has eliminated two H+ ions from the water, causing the ratio of hydrion to hydrate to swing in favor of the hydrate. The resulting equilibrium causes the PH to then go up. 40 If you have carbonate in your water, the pH can only go down so far. The lower the pH gets, the closer it gets to reaching the balance point that would be considered equilibrium between the hydrion and the carbonate. When you add more acid beyond that point, increasing the concentration of hydrion, you cause the carbonate to collide with the hydrion more often, and the carbonate/ hydrion interaction steps up to re-establish equilibrium. That keeps your pH from going down until you have reduced the carbonate concentration far enough.

I should mention here a very common misconception. People talk about having acidic water or alkaline water, based on whether their water is above or below a pH of 7.0. This is not entirely accurate. While it is true that acid water with a lot of carbonate added to it will see a rise in pH, that is not directly related to the carbonate level. It is related to the ratio of H+ to OH- ions. The CO3- will react with the H+ and eliminate it This will cause more H20 to break up into H+ and OH- ions. Because there were already some OH- ions present. this shifts the ratio thereby raising pH and making the water basic.

While adding carbonate will make water more basic, to a point; adding a hydrate such as Sodium Hydrate (NaOH) will not make the water more alkaline. In other words adding hydrate will not make the water pH stable or able to resist a drop in pH.

If you finish this section of the discussion and remember only that alkalinity is a resistance to a drop in pH, and not a high pH in and of itself, then you will have understood something significant.

Other anions can also cause alkalinity. Commercial pH "set and hold" additives are based on Phosphate. I don't particularly care for this stuff because it can lead to algae blooms. One family of plants I seem to have no problem growing is algae.

One last note about alkalinity. While it is sometimes referred to as buffering capacity this is not entirely accurate. Some buffers will resist a rise in pH. Alkalinity is strictly a resistance lowering of pH. These "acid buffers" are not likely to occur in your tap water so we don't need to worry about them in our discussion.

Conductivity:

Let us consider again our ion soup (or consume or stew, depending on your water supply). All of these cations and anions swim around in water with either positive or negative electrical charges. This means that our cations have extra protons and our anions have extra electrons. If you will remember our discussion on the basics, these extra electrons are there because they are wanderers, and don't mind bouncing from ion to ion.

Earlier, I mentioned that electricity, in layman's terms. is the movement of these electrons. So the presence of these ions and their associated wandering electrons makes it possible for the water to conduct electricity by pushing these electrons around. Logically, the more ions. the more mobile electrons and the easier the electricity travels through the water. This ability to conduct electricity is ca1led conductivity.

What conductivity does for us fish keepers is to give us a rough estimate of how much stuff is dissolved in the water. There are always things dissolved in most water, primarily organic compounds that are covalent bound and have no impact on conductivity. By measuring conductivity, we get a rough estimate of how much ionic solute is in the water. Amazon and West African fish don't like a lot of it, and will be less likely to demonstrate their parental instincts when conductivity is high.

Conductivity is measured in "Siemens" and these measurements are achieved by use of an electronic device appropriately named a conductivity meter. Water that is low in dissolved ions can measure ten microsiemens less.

Summary: So we need to understand some things about these various parameters and their inter-relationships. Here's the basic rule one must remember when measuring and adjusting water:

I) You can't lower pH and keep KH high. It simply won't work.

2) The more stuff you add to your water without evaluating the chemical makeup, the further you will get from what you really want.

3) Most of what you add to the water will raise conductivity, and upset your soft water fish.

Most importantly remember the "KISS" (Keep It Simple Stupid) rule. Ask about different approaches to solving your water parameter problems. When someone hands you a bottle of .'Super Fix-It-All" and can't define how it works in terms of the ionic soup, go elsewhere and ask someone else. The answers are there and sometimes it takes a lot of homework to find them. Now you have the understanding needed to search along a more fruitful path to find your answers. Water in every area is a little different and each of us has a need to figure out what is best for our circumstances.

Good luck in your search and keep 'em breeding. Oh yeah, did I mention regular, scheduled partial water changes? □