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Discussion Starter · #1 ·
Our 72 gallon tank currently has a pH of 7.8 and kH of 3. We are going to get an Oscar and want to lower the pH and raise the kH. How can we do this? We have some Cichlid Buffer we use on our African Cichlid tank to maintin kH levels, but I believe that also raises pH. Any advice would be much appreciated. Thanks!
 

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but I believe that also raises pH
You're right , it will. A few questions so I can better understand and maybe help.

Why do you want to raise KH?

What's the GH of the tank water?

What are your tap water values for pH, KH, and GH?

What size tank and what are the other tank mates?
 

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Discussion Starter · #3 ·
to answer your questions:

- I thought that oscars needed a kH of around 7-8. Is that not true?

- I have no idea what the GH of the tank water is. I am fairly certain our tap water is on the softer side.

- our tap water: pH = 7.2, kH = 0, GH = ?

- our tank is 72 gal and right now has 2 clown loaches in it

Thanks.
 

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I don't know of any fish that require a specific KH value. You'll never see KH listed in water requirements for fish. You may be thinking of total hardness, which is GH. Even with that, no fish requires a specific GH value. Some do better in a range or will only breed in a range.

From what I've seen, oscars prefer a softer water. It seems to me that they'll probably do just fine with the water that you have. I wouldn't even bother lowering the pH. It'll lower on it's on as the nitrogen cycle acidifies the water. KH will actually drop between water changes, and pH with it.

You need to just be concerned with KH dropping to 0 and pH dropping drastically to < 6 as a result. Frequent partial water changes with what you have should be just fine, particularly if your tap is a bit soft. Go for stable values within an acceptable range rather than adding stuff aiming at attaining a specific value. Frequent partial water changes will accomplish that, assuming the tank is not overstocked or overfed.

If you can get and post your tap pH, GH, and KH, I could confirm the recommendation to just go with the tap as is. First choice is always to just use the tap as is, if possible, rather than trying to adjust it with additives. Most fish do very well in a wide range of values.

I have rift lake cichlids and buffer a bit just to avoid pH crashes. My values vary a bit from reading to reading and the fish are no worse for wear.

Most other posts I've seen here would confirm that reaching and maintaining a specific value for most fish just isn't necessary. Good nutrition, compatible tankmates, clean, well filtered water, and frequent partial water changes are more important to focus on.
 

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prov356 said:
I don't know of any fish that require a specific KH value. You'll never see KH listed in water requirements for fish. You may be thinking of total hardness, which is GH. Even with that, no fish requires a specific GH value. Some do better in a range or will only breed in a range.
I would disagree on that. Many fish specifically like harder or softer water. While it is true that they may live well beyond their preferred range they will not be as healthy, or have as good of color if the hardness parameters aren't what the species needs. The ranges are much wider than ph and fish don't require a narrow range down to the degree, but it definitely matters in some species. From personal experience my africans show much better color when the hardness is over 9 degrees.

That being said I think O's are one of the species that don't care too much about it so for this specific situation i would agree that what is coming out of the tap is fine but I would buffer up the KH some just to keep the ph stable. Baking soda is very cheap compared to fish store additives for this by the way.
 

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I would disagree on that. Many fish specifically like harder or softer water. While it is true that they may live well beyond their preferred range they will not be as healthy, or have as good of color if the hardness parameters aren't what the species needs. The ranges are much wider than ph and fish don't require a narrow range down to the degree, but it definitely matters in some species. From personal experience my africans show much better color when the hardness is over 9 degrees.
There are two different types of hardness, GH and KH, total and carbonate. You're lumping them together. When referring to water hardness in the hobby, we speak of GH, not KH. KH is better referred to as alkalinity or buffers instead of carbonate hardness, at least in the aquarium hobby, in order to avoid confusion like this. You'll find water hardness preferences listed for fish, but they're referring to GH, not KH, although KH can contribute to GH. Gets confusing, I know. :D

There are some good articles in the library on water chemistry that explain this better that I can.
 
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