Ph, Gh and Kh for beginners. Have I got this right?

[dalto]

While this is true, it translates very poorly into practice, as large bodies of water effectively dilute the acidity, negative acid accumulation somewhat. But in small tanks, the lack of KH is potentially dangerous as there is nothing to prevent pH drops.

Keep in mind, my comment was in relation to fish needing KH to be healthy, not the impact on pH which is in a different spot.

About the 10x pH issue: I think your diagram is inconsistent. The way you represented it is that 7 is the middle. That is true if you are referring to BOTH alkalinity AND acidity. As the acidity increases, the alkalinity decreases, so that when the pH=7, the alkalinity and acidity are equal. Basically, with your scale, with numbers under 7 you are referring to the acidity and above 7 you are referring to the alkalinity. Does that make sense? The way your diagram showed it, 7 was the middle. I think you were trying to show both the acidity and the alkalinity but that won't work with the type of diagram you made.

For example: this is a diagram of the acidity and ONLY the acidity changes as the pH changes.

(1)10000000x-(2)1000000x-(3)100000x-(4)10000x-(5)1000x-(6)100x-(7)10x-(8)1x-(9)0.1x-(10)

Honestly, I think to make this information consumable you should insert a picture here to represent this.

Something like this:

or this:

Depending on what you are trying to show.

 

[Kittykat364]

Yes I agree with the pictures. I just wanted to stick with the same format she had for clarity sake


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[Masha]

Thanks again! I really appreciate the input. I'm working my way through the suggested changes now.
(By the way, in case you are wondering, this article is only for my own learning needs and if it's good enough I'll probably link to it when trying to help people here on the forum, but it's not for publication anywhere)

Here is the link to the ongoing Google Doc. I've only started making the changes.

https://docs.google.com/document/d/1m7JYvmV4sKAVV_3DUG9NdOr_yicGr2-HgKovTHAE3qY/edit?usp=sharing

To save you having to click there and comb your way through it, here are the changes I've made so far.

Keep in mind that I'm trying to give beginners the tools they need to understand these ideas in the context of aquarium keeping. So I'm only including the bare basics that are directly relevant to what's going on in the tank.

That means keeping things really simple, but hopefully not dumbing down too much.

Here is the re-written section on pH

-----------------------------------------

pH
pH is a measure of how acidic or alkaline water is. A ph of 7 is neutral. Above 7 is alkaline, below 7 is acidic. The higher the value, the more alkaline, the lower, the more acidic.

This one is important:
The pH scale is a logarithmic scale, which means that the values in the scale (5, 6, 7, 8, 9 and so on) don’t represent equal amounts of change in acidity or alkalinity. The pH scale is not like a ruler, where the distance between 5cm and 6cm = 1cm and the distance between 6cm and 7cm also = 1cm.

The scale works from 7 outwards, with the difference between each step increasing significantly as the acidity or alkalinity increases. The image below is not accurate in terms of the proportions, but it gives a general idea. As you can see, the difference in acidity between pH6 and pH7, is not as big as the difference between pH5 and pH6, and the same is true for the difference between pH7, pH8, and pH9.

The reason it’s important is because fish are so sensitive to changes in pH. From the point of view of the fish, a change from pH6 to pH5 will be a lot more shocking than a change from pH7 to pH6.
-----------------------------------------

Now I'm working on the KH section. Procrastination, here we come!

 

[Masha]

I've colored the biggest changes. Hope this is closer to accurate now.

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pH and KH- “Buffering”
KH stands for “Carbon Hardness” and measures the carbonates the water contains. This would include, for example, Calcium Carbonate, which is a common ingredient in water from areas with “hard” water. You may have seen the white deposits left behind when such water evaporates - that is Calcium Carbonate.

The KH and pH measures are related. Carbonates make the water alkaline, so the higher the KH, the higher the pH.

KH is also referred to as the water’s “buffering ability”. If the water has a good “buffer” it means that it is less likely to change its pH value. In other words, if the water in your tank has a low KH value, this means that various events (cycling the tank, adding rocks or driftwood etc) are likely to make that pH value change quickly. If the tank has a high KH value, apart from the fact that the pH will be higher too, whatever happens in that tank, it’s unlikely that the pH will change much. High KH = more stable pH.

If you needed, for some reason, to lower the pH of the tank, you’d have to lower the KH as well. Not just because KH increases the alkalinity, but also because KH makes it harder to change the pH.

This is one of the reasons it’s not a great idea to use only distilled water in a fishtank. Distilled water sounds great: it’s pure, right? Distilled water pH is neutral (7) and it has a KH of 0. No carbonates at all in distilled water. That means that a tank full of distilled water can change its pH easily and rapidly, a very bad idea for the fish.

Some fish are adapted to “soft” water with low KH value, because that is what is natural to the areas they are originally from. Some fish do better in water with a higher KH. But in general, if a tank has a low KH, it will be vulnerable to big changes in pH, so when keeping fish in such conditions, you’ll need to be extra vigilant.

Other reasons KH is important
Calcium Carbonate (one of the carbonates measured by KH) is also important to the health of your fish, plants and invertebrates. It’s needed for bone and teeth development, it helps regulate blood flow, helps the immune system and metabolism, and also promotes healthy heart.

This is another reason why distilled water is not the best for fish. It contains none of the essential minerals such as Calcium Carbonate.
GH
GH measures General hardness. It measures the amount of all the minerals in the tank, including the carbonates. So you can see that KH and GH are related . GH measures a number of minerals, but the ones that are the most important in the context of aquarium keeping, are Magnesium and Calcium. Magnesium is just as important for fish health as Calcium Carbonate. It aids digestion, immunity, growth, gill development among other things.

 

[RadMax8]

Masha,

I know you said this isn't intended for publication, but when this article gets to a final state, it might be a good candidate for the "Articles" section of Aquarium Advice, or at the very least a sticky. This would allow good visibility for new people or people wanting to learn more about the hobby.

Nice work, to you and everyone suggesting edits!


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[Masha]

That would be wonderful, Radmax!

 

[Kittykat364]

That's a great idea.

I'm not sure if it's just me but I thought KH was carbonate hardness? You say it's carbon hardness.


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[Masha]

That's a great idea.

I'm not sure if it's just me but I thought KH was carbonate hardness? You say it's carbon hardness.


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Whoops. That's a plain old mistake. Will fix. Thanks!

 

[Kittykat364]

No problem, this is going to be an awesome guide. So many people will benefit from this


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[Rebel1970]

I have a question about GH testing. I have a water softener. My KH measures 6. I am at 40 drops of GH test solution, and the water is as yellow as it was at 2 drops. Is the softener screwing up the Gh test?

 

[dalto]

I have a question about GH testing. I have a water softener. My KH measures 6. I am at 40 drops of GH test solution, and the water is as yellow as it was at 2 drops. Is the softener screwing up the Gh test?

Yes, your water will test at 0 if you have a softener. It is important to note that your water is not really 0 dGH, it just tests that way because the test only checks for calcium and magnesium. The water softener replaces calcium and magnesium ions with sodium or potassium ions. Test water from an outside faucet.

 

[Cold Canadian]

This is a very nice guide but you might want to add methods to change GH like you did for KH. Over all this is awesome and my understanding is 10x better


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[Rebel1970]

OK here are some new facts and questions about GH testing. I retested my water, before and after the softener. Then I tested my neighbors non softened water. Same results. My water after 4 drops and up to 60, I have yellow water all the same color. I tested my neighbors up to 75 drops with my GH test kit. Same thing, yellow water and no change in color up to 75 drops. I will have a LFS test my water, and I will test the source. Maybe I have a bad test kit. If I understand the test correctly, the water color is supposed to go from yellow to green. Not in my test cases. Any suggestions would be appreciated. Thanks in advance.

 

[trennamw]

Someone may have already said this but it'd be better to say that KH "influences" pH. It isn't as directly causative as your language implies. Earplugs don't make the kid stop playing the drums, they buffer the sound for your ears.




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[Masha]

Someone may have already said this but it'd be better to say that KH "influences" pH. It isn't as directly causative as your language implies. Earplugs don't make the kid stop playing the drums, they buffer the sound for your ears.




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This is one of the areas where I feel very uncertain about my knowledge.

I understand your analogy when applied to drums and ears, but not when applied to KH and pH

 

[trennamw]

This is one of the areas where I feel very uncertain about my knowledge.



I understand your analogy when applied to drums and ears, but not when applied to KH and pH

There is a lot I don't understand either.

But I think pH has to do with the amount of hydrogen ions in water ... And KH measures the amount of stuff you have to bond with the ions, turning them into something else. That's right off the top of my head a decade after intro chemistry. I could be laughably wrong. The first time I described my understanding of KH to a chemist friend he did laugh.

Buffers I believe are things that sort of deactivate acids. Aquariums have all sorts of acid producing situations, and the KH measures how much you can nullify those acids?

Maybe it's correct to say KH is the Tums of the aquarium? Lol. It doesn't create alkalinity, it just prevents acidity?

Again I'm pulling this from who knows where but maybe it's a jumping off point for you to look into more.

Great project. The explanations out there of GH and KH are terrible!




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[trennamw]

OK here are some new facts and questions about GH testing. I retested my water, before and after the softener. Then I tested my neighbors non softened water. Same results. My water after 4 drops and up to 60, I have yellow water all the same color. I tested my neighbors up to 75 drops with my GH test kit. Same thing, yellow water and no change in color up to 75 drops. I will have a LFS test my water, and I will test the source. Maybe I have a bad test kit. If I understand the test correctly, the water color is supposed to go from yellow to green. Not in my test cases. Any suggestions would be appreciated. Thanks in advance.

It goes from orange to green in one test, and blue to yellow (or vice versa) in the other.

If it looks yellow to you it might be green, it's hard to tell. The green is yellowish and the orange is peachy. But with that many drops it should be bright orange or bright green. Have you tried test strips? Five packs are cheap and you can post a photo.

Your LFS should have an idea of what the norm is for water in your area, as will your water bureau.

I like to do the GH and KH in a shot glass set on a piece of white paper, stirring with a toothpick with one hand while adding drops with the other. You also can look down the test tube to concentrate the color, that makes it clearer whether it's orange or green.


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[dalto]

Great project. The explanations out there of GH and KH are terrible!

GH to me is fairly simple. My understanding is that it is simply the amount of mineral ions in the water. That being said, every GH test kit/strip I have ever seen only measures the magnesium and calcium. One of the battles I constantly have in my mind is whether GH really matters to fish or if TDS is really what we should be measuring instead. I have not seen any research on this.

It goes from orange to green in one test, and blue to yellow (or vice versa) in the other.

I have had trouble using the API liquid tests if you have very low KH or GH. The color change happens so early that it is hard to tell what color it is. The strips work better but they provide a very imprecise measure. If anyone has a test they feel works well for low GH/KH I would love to try it.

 

[aqua_chem]

The relationship between pH and KH is complicated. KH is the sum of both carbonate (CO3--) and bicarbonate (HCO3-). pH in freshwater is majorly governed by the relative ratios of carbonate, bicarbonate, and carbonic acid via the Henderson Hasselbalch Equation. Note that the KH can be very low and the water have a very basic pH; alternatively, the KH can't be really high and the pH very low because the buffer will be consumed by shunting hydrogen ions onto bicarbonate, which creates carbonic acid which subsequently decomposes into CO2 and H2O.


Now, carbonates in solution will always be a buffer, in that there will always be some amount of its conjugate acid/base. What throws a (figurative) monkey wrench into the (literal) equation is the addition of non-balanced species, that is, carbonates not in solution in one particular form, such as limestone (CaCO3), or acids without strong conjugate bases such as organic acids from wood or acid produced from fish waste.

From wiki:

Limestone dissolves and adds a glut of CO3 into solution, which is [A-] in that equation. Some is converted into HCO3- rapidly as the solution reequilibrates, but much will remain stuck in the numerator of the log, and as such will effectively increase the pH. Alternatively, additions of acids as above convert [A-] into [HA], ie it gains a hydrogen ion (H+). This causes the [A-]/[HA] fraction to get smaller, which decreases the pH.

 

[trennamw]

GH to me is fairly simple. My understanding is that it is simply the amount of mineral ions in the water. That being said, every GH test kit/strip I have ever seen only measures the magnesium and calcium. One of the battles I constantly have in my mind is whether GH really matters to fish or if TDS is really what we should be measuring instead. I have not seen any research on this.

I saw some somewhere a long time ago. There was a suggestion that ... Oh **** I forget the name ... Some bacterial infection ... Has to do with mineral deficiency. There's a site selling a product, wonder shells I think, that increase GH. They cite a lot of research, I haven't looked into how reliable it is.

But I figure fish, like all animals, need minerals. And as in humans, not being disease-provoking-deficient doesn't mean your levels are high enough to be well. I understand fish physiology is similar to humans ... Which is why Epsom salts are a relaxant and laxative for us both.

have had trouble using the API liquid tests if you have very low KH or GH. The color change happens so early that it is hard to tell what color it is. The strips work better but they provide a very imprecise measure. If anyone has a test they feel works well for low GH/KH I would love to try it.

Yeah that's the water I have. I found the test strips to match the API tests for hardness, just not for ammonia and nitrates and stuff.

Sometimes with hard to read tests I either dilute it .5 ml tank water and 4.5 ml distilled then multiply by 10, or the opposite (use 50 ml tank water and divide by 10). I'm sick and can't figure out which applies here, lol.

Aqua chems explanation is awesome, but hard to translate into simple terms .


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