Simply put buffering is the ability of water to resist changes in pH. Many people comment about the importance of a stable pH and having a buffered system. The importance of pH is vastly overrated as aquarium product suppliers want to sell the unsuspecting newcomer a bunch of “pH Up”, “pH Down”, “Malawi Buffer” or “6.5 pH” products. It is just not important.
This is examined in more detail in this link:
4.4.1. pH is not Important
A high carbonate content (i.e. a high KH) buffers the water and prevents something called a “crash”, so many key in on KH. But “crashes”, where the pH becomes very low, only occur in very poorly maintained tanks or new tanks where the water is rarely or never changed. It is something called “Old Tank Syndrome” and is rarely encountered. During intensive cycling with a lot of ammonia it becomes necessary to add a carbonate or a bicarbonate to keep the pH above 7.0 with a KH over 1.
Buffering the pH up with Acidic Waters
One very easy way to make soft or acidic water fine for any fish is to use a bag of crushed coral, aragonite sand or crushed shells in the filter. This buffers to an excellent 7.6 to 7.9 pH. This is an excellent pH even for Amazon fish. But note that the “7.6 to 7.9” is an average. At times an aquarium with crushed coral can be 6.9 pH and at times it can be 8.5 pH. This is because of variations in dissolved carbon dioxide which occur naturally in any aquarium.
Crushed coral and aragonite take days or even weeks to work. If they are placed in an area of high flow like inside a filter they will work much better. If they are placed in a bag in a corner of the aquarium where there is no flow they might takes many months to work.
And crushed coral will typically but not always only last three to six months before it becomes coated in highly insoluble phosphates. It typically needs to be replaced every few months.
Baking soda will also raise the pH. Baking soda CAN, in sufficient quantities, raise the pH higher than crushed coral, all the way up to the 8.5 pH range. Note that baking soda also takes time to work. So adding baking soda should be done slowly. Add some baking soda to the aquarium and wait two days. If you are above 7.5 stop. If you are below 7.5 add more and wait four days.
Alternatively, a commercial aquarium buffering agent can be used if you like burning money. All commercial high pH buffering agents are simply baking soda and a small amount of other salts with a very high price tag.
Note that carbon dioxide, carbonate hardness (KH) and pH are interrelated in very convoluted and complex chemical pathways. This is the “Bermuda triangle” of the aquarium chemistry. Go there and you may never come out. I’m a chemist and I don’t try to control this triangle. Just keep the pH between 6.5 and 8.5 and total dissolved solids above 60 ppm and ignore the rest. The topic is covered in some depth in this link:
4.5. Water Hardness
Buffering to a Lower pH
For buffering lower pH one can use commercial buffering chemicals available in aquarium suppliers web pages. I don’t recommend commercial 6.5 or 7.0 buffers because they are all phosphates, and phosphates will give you huge problems with algae growth. Also if you have water with any degree of KH (over 4 degrees), acid buffers just won’t work.
Seachem sells some acid “buffers” which don’t have phosphates in them. These are sulfites and other sulfurous acid compounds. They do bring down the pH just like pool acid will bring down pH but they DO NOT buffer.
Buffers by definition hold a pH at a set value against the addition of either bases or acids. Seachem low pH “buffers” don’t do that in the 6 to 7 pH range, they only lower pH. They do NOT buffer, they are simply acids. There is a BIG difference. Sulfurous compounds buffer in the range of 4 to 5 pH, not in the range of 6 to 7 pH.
This means it is very easy for an aquarium “buffered” with the Seachem “buffer” to drop to 5.5 pH which could stall the cycle completely (and make nitrite quite poisonous). This is not desirable. One shouldn’t use Seachem low and neutral “non-phosphate” buffers simply because they are NOT buffers.
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pH in Depth
For those interested in a more in depth discussion of pH click on the following links:
Link to general discussion of pH:
4.4. Aquarium pH
Link to a more in depth discussion of pH and how unimportant it is in the aquarium:
4.4.1. pH is not Important
pH goes up and down constantly in an aquarium because of carbon dioxide and how it interacts with water. This is another relatively complex topic:
4.4.3. Carbon Dioxide and pH
There are situations when one has a pH greater than 8.5 and one needs to drop the pH. This link covers how to safely drop the pH of water
4.4.4. Dropping pH
And sometimes water out of the faucet that has set for two days has a pH less than 6.5 or 7.0 and needs to be raised. This link covers how to safely raise the pH:
4.4.5. Raising pH
Many people think that fish which have been bred in a wide range of waters can thus tolerate a wide range of water. This is simply a myth.
4.7. Fish Tolerance to pH
And many think that fish must be kept in a very stable pH or temperature and that rapid changes are detrimental to the fish. This is yet another myth.
4.8. Stability Isn’t Important
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Return to Temperature, pH, KH and GH
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Aquarium Science Website
The chapters shown below or on the right side in maroon lead to close to 400 articles on all aspects of keeping a freshwater aquarium. These articles have NO links to profit making sites and are thus unbiased in their recommendations, unlike all the for-profit sites you will find with Google. Bookmark and browse!
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Jeremy says
Even for you? No way, but I am honoured.
P.s. please reach out if you need a hand with web hosting.
Also, on a very personal note, do you have contingencies in place for the website to live on as your legacy?
Dave says
In reply to Jeremy …..You’re getting way too esoteric for me.
Jeremy says
Do you think that protein utilisation IS usually high? And usually that high?
Are you aware of any rate of tapering or a rate of protein utilisation in adult fish? As the fish in this experiment were growing fast.
Where I am heading with this, is thinking about:
Amount of food, protein in food => utilisation ratio => amount of NH3 excreted => via nitrogen cycle => consumes KH, results in NO3 increase
Trying to predict NO3 / KH impact based on food/protein given. Perhaps you’ve already run similar experiments with food/protein/NO3?
Cheers
Jeremy
Dave says
Jeremy … Yes, protein utilization is quite high. I would have said 95% utilization just from the impressions I have from reading on it.
Jeremy R says
Hi Dave,
I am hoping you’d be able to sense check my findings below?
I was looking back at this:
—–
I looked into the literature about protein utilisation vs NH4 excretion. This paper [(PDF) Effect of Dietary Protein Level on Growth Performance and Nitrogen Excretion of the Juvenile Convict Cichlid, Amatitlania nigrofasciata](https://www.researchgate.net/publication/261876280_Effect_of_Dietary_Protein_Level_on_Growth_Performance_and_Nitrogen_Excretion_of_the_Juvenile_Convict_Cichlid_Amatitlania_nigrofasciata), after a number of calculations which the authors didn’t perform, I calculated that the ratio of protein fed vs NH3 extreted was 0.17%. My calculations are available here regarding that article [Ammonia Excetion from protein calculation Juvenile Convict Cichlid – Google Sheets](https://docs.google.com/spreadsheets/d/1_cnTzaX3b0YKU0462AvBeWph4ly11UBUTGStSOTxzSw/edit?usp=sharing)
—-
it would suggest that the protein amount in the food (for the 40% protein food), is 99.83% used by the fish, with the remaining excreted into the water.
I find this value very high.
I thought utilisation vs excretion would be lower (eg 50%?)
Their results:
NH3 mg/kg fish / 6hr = 5.15
Calculated further:
grams of protein per day per kg of fish = 12.184
Total NH3 mg/kg fish / day = 20.6
NH3 (mg) / protein (g) = 20.6 / 1000 / 12.184 = 1.69 mg = ~ 0.17%
I really appreciate your help. Cheers
Jeremy R says
Yeah, and crushed coral is a bunch of things? And not too sure about redsea!
Thanks for the hot tip regarding the maximum size though.
I’ll run with calcite or, specifically, calcium carbonate.
Thanks again.
Dave says
In reply to Jeremy …… Calcium carbonate is calcium carbonate. Just make sure the particle size is somewhere under 1/4 th inch
Jeremy R says
Yeah… I found an older post of mine talking about the same situation in less detail. /facepalm.
Crushed coral here is about $10/kg (Caribsea Geo Marine Florida Crushes Coral Aragonite)
Rea sea reef base pink is about $6/kg
Calcite is about $5/kg.
Is there pros/cons given the price difference?
Thanks again.
Dave says
In reply to Jeremy ….. I would just throw a bag of crushed coral into the filter and forget about it.
Jeremy R says
Hi Dave,
Slight story to this one, but keen to hear your thoughts on how I should manage my tanks ongoing.
Since I have been setting up and running more breeding tanks and grow out tanks, I’ve noticed in some tanks, particularly those with higher stocking/ high feeding, I get a pH crash of 5 to 4.5 or so. This does quickly kill fish, and will usually wipe out a specific species in the tank, eg, Bristlenose will die while discus will be okay.
So thinking I’m negligent, lack of water changes etc, I was pretty bummed.
Anyway, so I tested my tap waters KH, it was 1 to 2 dKH (17.9 – 35.8ppm) , Looking at the Current water report for my area, the stats are:
– Total Hardness: 42-64 mgCaCO3/L (~2-4dGH)
– Alkalinity (total): 39.7 mgCaCO3/L (~2dKH)
– TDS: 147mg/L
– Total Chlorine: 1.26mg/L (as per the quarterly report, its 90% monochloramine)
So where does the bicarbonate go?
When ammonia is converted to nitrates through the nitrogen cycle:
( NH_3 + 1.5 O_2 → NO_2- + H_2O + 2H+ ) (ammonia to nitrite)
( NO_2- + 0.5 O_2 → NO_3- ) (nitrite to nitrate)
Bicarbonate is used via an overall simplified reaction involving bicarbonate as a buffer during the nitrification process to buffer the excess 2H+ created during the cycle above.
[ 2HCO_3- + 2H+ -> 2CO_2 + 2H_2O ]
Or, if calcium ions are present, it could also be:
[ Ca^{2+} + 2HCO_3^- + 2H^+ -> CaCO_3 + 2CO_2 + 2H_2O ]
Now, it gets a little tricky… At typical pH levels found in nitrification systems (around 7.0 to 8.0), the bicarbonate ion (HCO3-) is the predominant species. When the hydrogen ions are produced during nitrification, they can react with bicarbonate ions to form carbonic acid (H2CO3), which can then further dissociate into water and carbon dioxide.
This from what I can tell essentially continues to shift, consume, shift, consume, causing more H2CO3 to dissociate into HCO3- and H+, to maintain a pH balance, consuming more bicarbonate over time.
From what I read online, this equates to for every mole of ammonia that is consumed, 4 moles of alkalinity as bicarbonate is consumed.
Therefore, 7.14mg of alkalinity as CaCO3 per mg of ammonia oxidised.
So, given that, 1gram of fish food, with 55% protein = ~0.1067g of ammonia (assuming direct converstion and not metabolic utilisation)
So, lets now say:
– 100L Tank with fresh tap water
– 50 x 0.85g fish (~1g metabolic weight), fed at 2% body weight per day = 1g fish food
– Assuming no external additional bicarbonate / crushed coral etc
– Assuming 1gram of fish food, with 55% protein = ~0.1067g of ammonia, via converstion and not body protein construction
– Total ammonia / day = 106.7 mg
– Total alkalinity consumed / day = 7.14 x 106.7 = 761mg
– Alkalinity as per water report in a 100L = 39.7 x 100 = 3,970mg
– after a 100% waterchange, 3970 / 761 = 5.2days of alkalinity available.
I looked into the literature about protein utilisation vs NH4 excretion. This paper [(PDF) Effect of Dietary Protein Level on Growth Performance and Nitrogen Excretion of the Juvenile Convict Cichlid, Amatitlania nigrofasciata](https://www.researchgate.net/publication/261876280_Effect_of_Dietary_Protein_Level_on_Growth_Performance_and_Nitrogen_Excretion_of_the_Juvenile_Convict_Cichlid_Amatitlania_nigrofasciata), after a number of calculations which the authors didn’t perform, I calculated that the ratio of protein fed vs NH3 extreted was 0.17%. My calculations are available here regarding that article [Ammonia Excetion from protein calculation Juvenile Convict Cichlid – Google Sheets](https://docs.google.com/spreadsheets/d/1_cnTzaX3b0YKU0462AvBeWph4ly11UBUTGStSOTxzSw/edit?usp=sharing)
So taking this back into the bicarb consumption situation, its fairly minimal via the ammonia pathway.
Maybe there are other pathways that consume bicarbonate?
From a solution perspective, I’ve been adding sodium bicarbonate to my water, ~1dKH at a time, but its fairly onerous. Is Calcite better to use? Or something else?
Kind regards