What is pH?

pH is a measure of H⁺ (hydrogen ions).

It tells one how acidic or basic a solution is.

In the case of aquaria our solution is the water in our tank.

The pH scale goes from 0-14 with numbers below 7 being acidic and numbers above 7 being basic. 7 itself is considered neutral.

The scale is logarithmic meaning that the difference between adjacent numbers is a difference of 10.

ex.
3 is ten times as acidic as 4.

:goodpost:

I think this should be pinned. At one point in time or another, these questions about water chemistry will certainly be asked...whether outright, or just thought, something like this for people to read will be very helpful. :)


Great idea! jay

pinned.

Continue on, Mr. Glaive. :D

Ok good enough reception for me :D.

What is hardness?

Very simply hardness is the measurment of certain particles in a solution.

Once again we can assume our solution is our tank water.

When one refrences hardness one is usually meaning total hardness.
Total hardness is made of two components, carbonate hardness and general hardness.

What is carbonate hardness?

KH = short hand for carbonate hardness.

Carbonate hardness is the measure of carbonate and Bicarbonate anions in a solution, most accuratly depicted as parts per million or ppm.
An anion is a negative ion, and ion is a charged particle.
This is what many of us in the aquarium call buffering or buffering capacity.
I will explain this later.
I have heard this being labeled alkalinity toss that term out the window it will only confuse you.

What is general hardness?

GH = short hand for General hardness.

General hardness is the measure of certain ions in a solution.
In the case of aquariums we are talking magnesium, calcium, and occasionally iron.
Again this is most accurately dipicted in ppm.
This is also known as permanent hardness, yet another useless term.

side notes:
For those who are more familiar I omit the term degrees because I find it to be as accurate as a test strip. For those that do not know degrees refrences a range of ppm.

Next up the relationship between hardness and your pH.

What is the relationship of hardness to pH?

It is the KH side of hardness that affects one's pH.

One's KH affects one's pH in the following manner:

If you remember from the pH discussion I stated that pH was merely a measure of the H+ ions in a solution.

In the hardness discussion I pointed out that KH is carbonate hardness, the measure of carbonate anions in solution. Carbonate is also CO₃^2-.

What happens is the carbonate acts as a "basic" buffer to the solution.
Free floating H⁺ are attracted to the CO₃^2- and form bicarbonate or HCO₃^-, thus removing the hydrogen from the solution and maintaining or possibly lowering the pH.

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Minor note:
One source of hydrogen is the cycle itself, there are acidic compounds that are biproducts of a healthy tank with biological filtration.

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Notes:

When one is attempting to maintain a nuetral or slightly acidic pH one wants to work with softer water, softer meaning a low hardness. The GH is not going to have much, if any effect on the pH, however if one's KH were high they would have difficulty keeping a lower pH due to the natural tendencies of KH to raise pH.

Typically in hard water systems, such as african cichlid tanks, one will use "carbonic" rocks to raise thier KH.

Common carbonate rocks and materials:

• Texas holey rock <pretty looking limestone>
• Crushed coral
• Aragonite
• Dolemite

While all of those are esentially the same, CaCO₃ in solution:Ca²⁺ and CO₃^2- or MgCa(CO₃)₂,
they are formed differently so they disolve differently.

Where as in low pH softwater tanks people use other materials to lower thier hardness and pH.

Common pH and KH lowering materials and means:

• Peat
• Wood
• CO₂ reactors
• adding Reverse Osmosed water <RO>

One common misconception water softeners don't soften water in a manner that works for your fish they merely exchange Mg²⁺ and Ca²⁺ for Na²⁺ ions.

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Next up:
Raising pH in a more natural manner


Future thoughts:
lowering one's pH and Hardness
Chemistry behind the "mythical" cycle
Differences in toxicity due to pH

Notice:
If you notice an error on my part please pm me the problem rather than commenting in the thread to keep it more on topic.
Also if you have requests for future chemistry related topics for the thread pm me.
If you have one you want to write yourself write it and pm it to me.
If your suggestion is used I will make it clear where the credit lies.
I am going to be somewhat picky on this thread due to my one back ground, I am however not infallable.
I have an extensive back ground in Environmental Engineering with an emphasis in water quality and watershed management.

Raising pH in a more natural manner.

I am a fan of finding natural ways to deal with problems. In my opinion it is rather dangerous for and inexperienced person to attempt to alter such parameters as pH or hardness with say baking soda. Most people would play the guessing game to figure out how much of what substance to add. It is far too easy to slip up when one can add rocks that will disolve only so far.

Different carbonate rocks

There many carbonate rocks out there, what truely sepperates them is thier ability to disolve or in more scientific terms thier "rate of dissolution".

Carbonate rocks: <pruned for that which you may find in aquaria and listed in order of dissolution form lowest to highest>
I Limestones
A Calcite
B Aragonite
II Dolostones
A Dolomite
III Metamorphic
A Marble

Limestones >> Rocks composed of CaCO₃.
Calcite vs Aragonite >> Calcite has a more stable subatomic structure.
Calcite >> Lower disolution of the carbonate rocks. Texas holey rock or coral for example. Begins
disolution at around a pH of 7.8.
Aragonite >> Aragonite sand is the most common form that comes to mind. Begins
disolution at around a pH of 8.2.

Dolostones >> Rocks composed of MgCa(CO₃)₂.
Dolomite >> Upon looking at the chemical formula we see that for every part that
goes into solution one gets 2 carbonates. It's disolution is a tad bit higher than the
limestones group.

Metamorphic >> I won't go into detail but from tests in the past using RO water crushed marble has driven pHs in excess of 10.0. Much to powerful for aquariums IMHO.

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I have personally that in my own water which is basic and hard out of the tap that crushed coral is enough to maintain my KH and therefore pH. However this may differ for you. There are so many factors with regards to altering pH and hardness naturally that I can not go into them.

These rocks can also be used if you have truly acidic water, for example areas of Vancouver Canada that have a tap water pH of 6.0.

The trick is in learning how much to add, this is where a 5 gallon bucket and a powerhead come in very handy. One can add tap water to the bucket and place in it a powerhead and say 1/4 pount of material. Then one waits 24 hours and tests the water.

Pretend your target pH was 6.6 and after the first test the pH read 6.3. You would know to add another 1/4 pound and run the test another 24 hours. If the pH was 6.6 in the next day then you would know that you needed 1/2 pound of your test rock per 5 gallons of aquarium water to maintain a pH of 6.6.

The same can be done for any attempt to raise pH be it on the acidic side or the basic.

It the case of Seedy who has a lot of breeding tangs that probably prefer a pH of 8.8-9.2 he could say do this experiment with dolemite and see if he can't avoid the chemical game. <Sorry to use you as an example Seedman.>

In some cases the ammount of material needed for the change in pH will not be practical, if this is the case aim for close, or chose different fish.

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Another note:
In the case of doing this with existing inhabitants, you want to increase the pH slowly try to not exeed .2 incrememnts in a 24 hour period. So for example if you knew that 5 pounds of material would raise your whole tank 1.0 on the ph scale I would suggest taking the five days and doing a pound a day.

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Hopefully this was not too complex, I did try to stay away from too many formulas.
If you have any confusion pm me and I will address it there as well as an edit in here if need be.

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Next up lowering pH

future:
Chemistry behind the "mythical" cycle
Differences in toxicity due to pH

Lowering pH is not an area I have personal experience with in aquaria. So here I am relying on what I have read and what I remember from my lab days. This is an area in which user comments dirrected to my feedback thread would be appreciated.

It is my understanding that loweriung pH is more stressful to fish than raising it, so I would deffinetly stick to teh 0.2 per day rule.

Means of lowering pH:

Peat

CO₂ bubblers

Reverse Ossmossed water

Distilled water

Commercial resin pillows

I have listed these in order of safeness in my opinion. They are all effective means though some are more cost effective. I do not like chemically altering pH so the pillows are way low on my list, even though any of these can be considered chemically altering.

The use of peat is very simple one puts peat in a media bag and places it in a area of decent flow, I would choose my cannister for this personally. The peat naturally absorbs carbonate and calcium which in turn reduces pH. I ca not recomend an ammount I can merely tell you mimic teh buscket method for raising pH.

CO₂ bubblers reduce pH by having an acid as a by product. The rough of it is the CO₂ reacts with carbonate to form carbonic acid. This is yet another trial and error method a deffinet bucket tester.

RO water is water that is pushed through very fine membranes slowly. This reduces all particles to nearly nothing and seems to take the pH to about 6.8 on my mother's unit. One basically mixes tap and RO water to get the desired pH.

Distilled works in the same manner as RO water.

Pillows have a resin in them that works in the same manner as peat, but in the long run costs more.

That is a very rough first draft I will revist it Later I just am not in the right space to be finishing this part up, so I will move on.

This will be covered in two parts, the first being a lighter overview and the second being the chemical formulas. Try not to let it scramble your brains. :D

Nitrogen Cycle lite:

The nitrogen cycle is the process by which ammonia is converted to nitrite and nitrite is converted to nitrate. Biological filtration is essentially the nitrogen cycle.

In your tank there are many sources of waste that contribute to ammonia, the following are common..

Fish waste:
excrement
urea
ammonia from respiration

Decay:
plant matter
excess food

All of these are or lead to what is refered to as ammonia. Though in truth depending on the pH of one's water they are a combination of ammonia and ammonium, this will be covered in later discussion.

Ammonia is very harmful while ammonium is not so much so.

Bacteria break down the ammonia into slightly less harmful nitrite.

When one is cycling a tank one's fish may die off due to nitrite poisoning. What most people forget is that the ammonia beforehand burned thier gills.

In turn another type of bacteria break the nitrites into less harmful nitrates.

Be warned even though nitrates are less harmful than nitrites and ammonia in a high enough concentration they too can hurt your fish. One example is stunting thier growth. Still another would be weakening them so that they are more susceptible to disease. I don't know of a case in which nitrtaes have dirrectly killed a fish however there are many cases in which it contributed.

Believe it or not that was chemistry, organic chemistry to be precise.

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Quick look at the initial cycle and then on to the brain drain.


Initial cycle:
When first cycling a tank one has to build up ammonia in order for the bacteria that convert it to be able to exist. If you had no food would you exist? No I think not. ;)

As the bacteria form they begin consuming ammonia and continue to do so until enough have cultured to keep up with the ammonia production.

Those ammonia converting/consuming bacteria convert the ammonia to nitrite. However the nitrite consuming bacteria can not live in an environment with ammonia in it, so they will only begin to culture when there is no more ammonia.
The nitrite converting/consuming bacteria culture until they have equalized thier food source, the nitrite. By now all the ammonia is nitrate and you'd better do a water change. ;)

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Minicycles:

Minicycles occur when the ammonia bacteria colony is damaged or over loaded.
This may happen do to a sudden rise in tank occupants or perhaps too much decaying matter such as a fish. Another cause is people washing thier biomedia media in chlorinated water or water that is vastly different in temperature.

The second would more than likely cause a "re-cycle."

In the case of a mini cycle, for whatever reason, there is ammonia in the system which kills the nitrite bacteria. It is rare in a mini cycle that one notices the rise in ammonia, usually we only see the nitrite spike. By teh time teh ammonia was detectable the nitrite bacteria is dead. The ammonia bacteria respond very quickly but the nitrite bacteria must rebuild from scratch.

A solution to this is too always have another cultured biomedia on hand in another tank. Just a few ceramic rings from a fluval for example can effect a 1-3 day turnaround as opposed to 2 weeks.

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Lets get serious:

First off the bacteria are really oxidizing the aforementioned chemicals.

Formulas:

ammonia: NH₃
Nitrite : NO₂^-
Nitrate : NO₃^-
Water : H₂O
Hydrogen: H⁺

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Ammonia and ammonium oxidization:

NH₃ + 2H₂O >> NO₂^- + 7H⁺

NH₄⁺ + 2H₂O >> NO₂^- + 8H⁺

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Nitrite oxidization:

NO₂^- + H₂O >> NO₃^- + 2H⁺

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Note the extra hydrogen ions and what this means to pH and better understand buffering, even at lower pH's.

Okay so I went easy on you here. ;)

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Side notes of some importance:
When one tests for ammonia with a kit you initial test tells you the total disolved ammonia and ammonium, ammonia is far more toxic than ammonium.
Then the test kit gives you a chart for your pH vs the initial reading. The chart lets you approximate how much ammonia you have in your tank.

In higher pH's there will be more ammonia due to there being less free floating hydrogen ions for the ammonia to bond with to form ammonium.

ie.

NH₃ + H⁺ >> NH₄

So cycling or mini cycles can actually be much more harmful to fish at higher pH's.

At this point I am not sure what else is needed for this sticky besides minor editing and a serious clean up on the lowering pH article. Iam still open to suggestions, but will consider 101 complete for now.

Per the request of Dtroup.

How does plants filtration work?

Well what makes a plant grow besides light?

Plants require ammonia, nitrate, oxygen and carbon dioxide to grow.

Plants draw water and nutrients through their roots, they breath out through their leaves.

So a plant consumes some ammonia and nitrate through its roots and breathes out
carbon dioxide or oxygen through its leaves depending on light. This is the basic idea of it's filtration.

A plant "exhales" oxygen when the lights are on and "exhales" carbon dioxide when the lights are off.

Hope fully that covers the subject well enough. If you want more a more indepth answer request it in the feedback thread.

Per the request of Dtroup.

Why do some rocks fizz when one puts a weak acid on them?

To explain this we need a weak acid and a rock that would fizz.

Weak acid: Acetic acid <vinegar> HC₂H₃O₂
Lime stone: CaCO₃

CaCO₃ + 2HC₂H₃O₂) >> Ca(CH₃CO₂)₂(s) + CO₂(g) +H₂O(l)

What this tells us:

Ca(CH₃CO₂)₂(s) is a "salt"
H₂O is water
CO₂ is a gas its formation in the reaction is the source of the bubbling.

Are these rocks safe for your aquarium?

These are perfectly safe in the aquarium if one wants a higher pH or in small quantities as a buffer. Many people use baking soda in thier aquarium and it has the same reaction.

Myth busted. << Have wanted to say that since Myth Busters first aired lol.

The rocks to avoid in general are the ones that may leach heavy metals
into the water. If you put a rock in a bucket of water and it forms rust or discolors in a wierd/non algae way avoid them.


PS
Next articles: (Not necessarily in this order.)
City water vs Well water
Salt and the fresh water aquarium