How Important is GH and KH for Africans?

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Harry Tolen

Cichlid Fan
Aug 17, 2000
Union, WA, USA
dcallen: what kind of "Africans" are you keeping, anway? Knowing that would help us make more specific recommendations, and you can see from the stats posted above that the different Rift Lakes have significantly different parameters.

I would not wait to check your tapwater before deciding what to do, by the way. Test the water from the tank. Tetra makes a test kit that includes tests for GH, KH, pH, ammonia, and nitrites, availale from the on-line retailers for about $15, that will do quite nicely.

Once you get those results, please post them here.

Incidentally, I would continue to add the buffers and Cichlid salts you have been using; as long as you are only dosing for the volume of water you replace during changes, you will not create a significant problem. Your pH being at 8.0 is an indication that you are not having a problem; that is a good number for Malawi and actually too low for Tanganyikans.

I should mention two other things: if you are adding only Cichlid salts, you are not significantly buffering the water. For that you need to use the separate buffering product. And sea salt is not a good thing to add to Rift Lake tanks, as their water does not naturally contain high amounts of sodium chloride.


The Spurs: World Champs again!
May 6, 2003
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Thanks for the advice. I will take some readings and post them to this thread. As far as fish go I have male Peacocks and one male Yellow Lab in the tank at the moment. I have 8 fish total in the 70 gallon tank.



Registered Member
Jan 7, 2022
im not sure about actual degrees but I know they like it hard :p (no pun intended)about 10 DH if not harder as far as the scratching that is sign of parasites usually.
Hummm. Interesting as I am thinking abt slooooowly, with the water changes probably, reducing the ph of my water. I’ve been running the Tanganyikan tank at 8.4 to 8.6, but that was ok during the summer when I kept a 65 gallon bin full or water premixed at 8.4. Winter changes are hard and I can’t use my python. I read the Tangier’s I have are sensitive to even minor ph changes. My winter water in Seattle tests 8.0 high range API. Right now my nitrates are wa to high due to tardy water changes. Any suggestions? This is my first T tank, but I’ve had five and increasing every spawn for some time. They breed like crazy and usually one or two survive. I got them as barely juveniles and they’re endangered species. Sure don’t want to lose them.
Apr 2, 2002
New York
Fish do not have a KH requirement. KH is temporary or carbonate hardness. it is easier for me to copy paste the below rather than write out the same explanation myself.

Buffering Capacity (KH, Alkalinity)
Buffering capacity refers to water's ability to keep the pH stable as acids or bases are added. pH and buffering capacity are intertwined with one another; although one might think that adding equal volumes of an acid and neutral water would result in a pH halfway in between, this rarely happens in practice. If the water has sufficient buffering capacity, the buffering capacity can absorb and neutralize the added acid without significantly changing the pH. Conceptually, a buffer acts somewhat like a large sponge. As more acid is added, the ``sponge'' absorbs the acid without changing the pH much. The ``sponge's'' capacity is limited however; once the buffering capacity is used up, the pH changes more rapidly as acids are added.
Buffering has both positive and negative consequences. On the plus side, the nitrogen cycle produces nitric acid (nitrate). Without buffering, your tank's pH would drop over time (a bad thing). With sufficient buffering, the pH stays stable (a good thing). On the negative side, hard tap water often almost always has a large buffering capacity. If the pH of the water is too high for your fish, the buffering capacity makes it difficult to lower the pH to a more appropriate value. Naive attempts to change the pH of water usually fail because buffering effects are ignored.

In freshwater aquariums, most of water's buffering capacity is due to carbonates and bicarbonates. Thus, the terms ``carbonate hardness'' (KH), ``alkalinity'' and ``buffering capacity'' are used interchangeably. Although technically not the same things, they are equivalent in practice in the context of fishkeeping. Note: the term ``alkalinity'' should not be confused with the term ``alkaline''. Alkalinity refers to buffering, while alkaline refers to a solution that is a base (i.e., pH > 7).

How much buffering does your tank need? Most aquarium buffering capacity test kits actually measure KH. The larger the KH, the more resistant to pH changes your water will be. A tank's KH should be high enough to prevent large pH swings in your tank over time. If your KH is below roughly 4.5 dH, you should pay special attention to your tank's pH (e.g, test weekly, until you get a feel for how stable the pH is). This is ESPECIALLY important if you neglect to do frequent partial water changes. In particular, the nitrogen cycle creates a tendency for an established tank's pH to decrease over time. The exact amount of pH change depends on the quantity and rate of nitrates produced, as well as the KH. If your pH drops more than roughly two tenths of a point over a month, you should consider increasing the KH or performing partial water changes more frequently. KH doesn't affect fish directly, so there is no need to match fish species to a particular KH.

Note: it is not a good idea to use distilled water in your tank. By definition, distilled water has essentially no KH. That means that adding even a little bit of acid will change the pH significantly (stressing fish). Because of its instability, distilled (or any essentially pure water) is never used directly. Tap water or other salts must first be added to it in order to increase its GH and KH........

Altering Your Water's Chemistry
Hardening Your Water (Raising GH and/or KH)
The following measurements are approximate; use a test kit to verify you've achieved the intended results. Note that if your water is extremely soft to begin with (1 degree KH or less), you may get a drastic change in pH as the buffer is added.
To raise both GH and KH simultaneously, add calcium carbonate (CaCO3). 1/2 teaspoon per 100 liters of water will increase both the KH and GH by about 1-2 dH. Alternatively, add some sea shells, coral, limestone, marble chips, etc. to your filter.

To raise the KH without raising the GH, add sodium bicarbonate (NaHCO3), commonly known as baking soda. 1/2 teaspoon per 100 Liters raises the KH by about 1 dH. Sodium bicarbonate drives the pH towards an equilibrium value of 8.2.
The above comes from
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