Very High GH/Very Low KH... Confused

Noidstradamus

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Hello. I'm fairly new to fishkeeping (6-7 months) and I've been trying to educate myself on water chemistry. There is something very perplexing to me about our tap water in our home in upstate NY. When I use an API GH/KH test kit on our tap water, I get very high GH readings (22 dGH) and very low KH readings (2 dKH). Our tap water is also right at about 7.0-7.2 pH. Is this something that anyone else has experienced? I don't know how to balance these things out without bumping the pH too high. Ideally I'd like to see 4-5 GH/KH and keep our pH neutral. is this possible?
 

Essjay

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It is unusual to see a GH that high.

Can I just check how you are measuring the GH.
I always found the colour change hard to see with soft water. The end point of the GH test is a colour change from orange to green but because the colours are very pale with only a few drops I could only see this colour change if I took the lid off the tube, stood it on a piece of white paper and looked down into it.


As a check - does your kettle or shower head get limescale build up? If your GH is actually 22 dH, there should be a fair amount of limescale.
 

Colin_T

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You can have a high GH with a low KH and vice versa. However, you normally get a high KH if you have a high GH
 

StevenF

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The GH test detects the pressence of Calcium and Magnesium (Ca and Mg) only. The KH test detects the pressence of caronate ions. CO3 only. Since the tests measure different things you can have mostly GH with low KH or high KH with low GH. And there is nothing wrong with either of these extremes.

So if your gh and KH are high you likely have mostly calcium carbonate and or magnesium carbonate. If your GH is high and your KH is low then you water is mostly made up of sulfates and Chloride Mg and Ca salts. And there are many other types of Ca Mg salts that might be pressent. Suflate and chlorides are the most common in most water sources and are perfactly safe for fish and shrimp.

As a check - does your kettle or shower head get limescale build up? If your GH is actually 22 dH, there should be a fair amount of limescale.
Limescale will only appear if the water is mostly Ca Mg carbonate. Ca and Mg carbonates don't dissolve easily and will build up on surfaces. However Ca Mg sulfates and chlorides are dissolve very easily and as a result very little to no mineral buildup will ocurre on sufaces.

I always found the colour change hard to see with soft water. The end point of the GH test is a colour change from orange to green but because the colours are very pale with only a few drops I could only see this colour change if I took the lid off the tube, stood it on a piece of white paper and looked down into it.

My understanding is that most of New York state has soft water. GH of 3 to 6. So you might want to repeat your test. Stop adding any adrops when you see the first int of a color change.
 

Essjay

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Stop adding any adrops when you see the first int of a color change.
That was my thought as well. With very soft water the colours are so pale it's hard to see any change.

The instructions on API's website don't use the word 'bright' but they used to say to look for a bright green which is very misleading. It's not the intensity of the colour that indicates the end point it's the shade.

One other point I need to ask - do you shake the tube after every drop of reagent?
 
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Noidstradamus

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It is unusual to see a GH that high.

Can I just check how you are measuring the GH.
I always found the colour change hard to see with soft water. The end point of the GH test is a colour change from orange to green but because the colours are very pale with only a few drops I could only see this colour change if I took the lid off the tube, stood it on a piece of white paper and looked down into it.


As a check - does your kettle or shower head get limescale build up? If your GH is actually 22 dH, there should be a fair amount of limescale.
The color is actually very noticable. On drop 21, the vial is a obvious and vibrant orange, on drop 22 it switches to a light, but still obvious, green.
 
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Noidstradamus

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The color is actually very noticable. On drop 21, the vial is a obvious and vibrant orange, on drop 22 it switches to a light, but still obvious, green.
Also another thing to add, a fish keeping friend of mine with a whole lot more experience than me also has very hard water. So much so that he invested in a whole him softener. His town water report shows very hard water. I'm two towns over and my report doesn't actually list the gh/kh like his. I'm pretty certain my numbers are right. It's not the first test I've done with this result. I'm more interested in the best way to balance the gh/kh so as to stabilize the possibility of big PH swings.
 

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