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Is there a chart/table with all water parameters and their explanation?


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I know ACO has put out a lot of videos about water parameters and those have been helpful but it seems like it would also be nice to just have one cheat sheet that has the common names, a quick explanation, and maybe common ranges (ie what is generally considered "moderately hard"?)

I feel like I'm starting to get a handle on it but I still find myself asking stuff like "Wait, is TDS the same as total alkalinity or is it GH?"

Most of the parameters have at least two names and some have different measurements (degrees vs ppm). This was really confusing getting into the hobby.

Does anyone know of a good cheat sheet like that? If not I may try putting something together but I'm no graphic designer...

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I can’t remember ever running across a comprehensive chart on the parameters needed for different species.  That’s typically something you just have to look up for each species you want to keep.  Most species are adaptable enough that the GH/KH/pH parameters aren’t too important as long as they’ve adapted to your parameters and your parameters are reasonably consistent.

In general, most cory species are soft water species, but some do come from harder water.  That said, most cory species are adaptable enough that it doesn’t matter as long as your tank parameters aren’t outrageously shifted to an extreme.  Same can be said with most pleco species, but many will breed just fine in the very hard water we have around here.  There certainly are species that are less adaptable but if you buy from a breeder that has similar water parameters, you should be OK.

Aqadvisor.com will usually look at that for you if they have each specie’s parameters programmed into its database.  It will pop up an alert if you list species that have widely divergent preferences or needs.  Then you’ll need to do some reading on how adaptable your species is, or isn’t.

Coop has a nice article here.  https://www.aquariumcoop.com/blogs/aquarium/ph-gh-kh and this arrival includes a chart that lists relative hardness about halfway through.

I also found this chart (below) in an article on liveaquaria.com that gets you a very general starting place and shows you how much difference there can be between types of fish - compare African cichlids with discus.  Big overlap on temp, no overlap on pH, no overlap on KH or on GH.  But I know people that keep discus and even breed them around my area that has notoriously hard water and high pH.  They are usually mixing in some RO, but don’t usually take parameters down to what’s typically recommended for discus and are still successful at breeding them and raising fry.  It’s usually fairly easy to raise African cichlids around here.  They really like our water, as do guppies and goldfish (as long as you can keep the goldfish from overheating too much).


Parameter Freshwater
& Discus
Brackish Pond
Temperature 72 - 82°F 72 - 82°F 76 - 86°F 72 - 82°F 33 - 86°F
pH 6.5 - 7.5 7.8 - 8.5 6.0 - 7.5 7.5 - 8.4 6.5 - 7.5
Ammonia 0.0 0.0 0.0 0.0 0.0
Nitrite 0.0 0.0 0.0 0.0 0.0
Nitrate < 50 ppm < 50 ppm < 30 ppm < 50 ppm < 50 ppm
Alkalinity (Carbonate Hardness) 4 - 8 KH 10 - 18 KH 3 - 8 KH 10 - 18 KH 4 - 8 KH
General Hardness 4 - 12 GH 12 - 20 GH 3 - 8 GH 12 - 20 GH 4 - 12 GH

So it really comes down to pretty basic needs:

First, figure out your tap and tank parameters (because they can be different).

Second, figure out the tank parameters that are ideal for the fish you want to keep.

Third, figure out how tolerant your desired species are to different tank parameters if your tank parameters don’t exactly match the fish you want.  In other words, are you going to have to routinely adjust your water parameters at every water change?  This will necessitate more frequent testing, possibly more frequent water changes, possibly remineralizer +/- RO water.

Fourth, figure out if it’s really worth it to you, to routinely adjust your tank parameters if the species you want absolutely won’t prosper in your normal tank parameters.  For my stupid high pH, very hard tap water, I mix RO to half and half for most tanks, a little more RO for just a few tanks.  I’m aiming for a happy medium since most everything I have is OK with “average” parameters.

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On 12/28/2022 at 12:11 PM, Odd Duck said:

I can’t remember ever running across a comprehensive chart on the parameters needed for different species

Thanks for the completed answer. I was talking more generally. Like if you Google aquarium test strips and look at their readout you'll see lots of different names for things.

Here is a random sample from a Google search:


GH is called Hardness, General Hardness, Total Hardness

KH is called Carbonate, Buffer, Alkalinity

Then some have Total Alkalinity as a separate parameter 

Then occasionally online, you'll find places referring to TDS


I think it would be helpful for beginners if there were some chart that translated all these names, have a one line description, showed how they relate, and gave general ranges (like that chart on the ACO defines soft vs moderate hard vs hard)

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On 12/28/2022 at 1:23 PM, nabokovfan87 said:

This is the one I use.  ACO has a very similar one. You can see the "needs attention" or "water change" type of warnings on the strip results.


That's interesting... This one has KH being Total Alkalinity where others (like mine) have it as it's own thing


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On 12/28/2022 at 1:31 PM, Schuyler said:

That's interesting... This one has KH being Total Alkalinity where others (like mine) have it as it's own thing

The chart that Odd_Duck posted is going to be the most thorough. In terms of what specific word is used, not really something to choose between. I think alkalinity makes sense because you're specifically talking about something that is tied to PH.

That being said, understanding what each thing is, that's the question, making it easy. The blog article linked is a great resource for that type of information as well.

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Ah, yes.  I see what you’re getting at.  Unfortunately, they are called different things in different languages and that carries over into English because we borrow everything.  So depending on which author you’re reading, or who they learned it from, it gets quoted many different ways.  Let me see what I can find.  Despite having far too many chemistry credits to my name to get my degrees, college was a long time ago and GH and KH were not such a big deal back when I was first learning about “aquarium stuff” back in the mid-70’s.

While it’s something that I have a basic grasp of the principles, it’s not something I’ve made myself study in depth until it’s second nature because I don’t find it that interesting nor necessary to be a good aquarist.  As long as you know what you have and what you need, you don’t actually need to know the gritty details of how it works, just the basics of what can happen in your tank at the extreme ends of the ranges.  Or if you have fish that do need specific ranges that don’t match your typical tank range.  If you’re running CO2, you will need to understand it since CO2 has potential to mess with these parameters much more due to pH changes.

I’m sure there are others that could explain better, but I’ll give it a whirl.  First, refer back to the linked ACO article and table and Irene’s excellent video about GH and KH.   Most anything I could post would just be redundancy and repetition from their articles, so I’ll try to just tackle the “units” used to see if I can clear that up a bit.

So mg/L can essentially be considered equal to ppm (parts per million) for both GH and KH.  It is slightly more complex involving molecular weights and such, but for practical purposes, it’s close enough for what we need.  The other common reference values are in “degrees of hardness’ - dKH, dGH.  Degrees of hardness is essentially equal to the number of drops of test solution used to get the results in the API Master Test Kit.  This is deliberate on their part and literally a function of the math when you calculate the concentration of the test solutions and the drops of test solution relative to the volume of tank water in the test vial.  They made the test solution so it would match.  I’m sure it matches whomever came up with the “degrees of hardness” idea instead of using ppm or mg/L like a normal scientist would.  😜 You can calculate your dKH or dGH to ppm (mg/L) by multiplying either by 17.9.

I think part of the confusion for KH and GH is that both are measuring for similar, but not quite identical things - KH is carbonate ions (from German Karbonate AKA Karbonathärte) which is very often calcium carbonate but can be other carbonates, and GH (general hardness) is primarily calcium and magnesium ions in the water.  To confuse things further, pH is often, but not always linked to hardness.  It is possible to have soft water and a high pH, but it isn’t common.  Usually high pH is associated with harder water and lots of “buffer”.  “Buffer” can be lots of things, but carbonates buffer very well and higher KH buffers well and nearly always is associated with higher pH.  Very low KH risks crashes if the pH starts to drop.

Then TDS is Total Dissolved Solids which brings in organic acids, proteins, hormones, sugars, etc, etc, etc, and tends to climb with planted tanks especially if they have a lot of rotting leaves, heavier bioloads, high feeding, etc, and is not necessarily linked to pH, GH, or KH. It does tend to climb with high KH and/or GH, but can be high even without elevations of these other parameters.  It is most often measured by using a conductivity meter and it does NOT tell you what compound(s) are detected, just that the conductivity of the water solution.

I don’t know if I’ve confused things more or if it helps any at all to focus just on the units and how they compare and potentially impact each other.




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Maybe if I give a scenario it will help.

Let's say a total newbie watches that girl talks fish video or reads the the ACO article then goes to look at their test strips they bought online because they were on sale and the test strips have different names for everything.

Or they look a fish species on Google and the site uses a name for a measurement they aren't sure of or it says something like "moderately soft" rather than an exact value range.

What I was thinking was a quick cheat sheet they could reference to be like "Oh yeah KH is the one that buffets pH" or "Ok so the carbonate on my test kit is the KH" or "My water would be considered soft"

Rather than digging through five descriptions of how acids give of a proton etc

Here's something I threw together that probably has issues


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On 12/28/2022 at 4:07 PM, Odd Duck said:
On 12/28/2022 at 5:38 PM, Schuyler said:

Here's something I threw together that probably has issues




On 12/28/2022 at 9:54 PM, modified lung said:

Make a list of everything you'd want on it and I can try to throw something together tomorrow.

If you think this would be helpful for other beginners too then that would be great.

I think if it had everything on that chart I made plus maybe ranges for what is considered mildly acidic, neutral, etc (similar to the hardness) that would be helpful.

I want it to have visual ques that show TDS encompasses the alkalinity, GH, and KH. Also that total apparently includes KH.

Maybe that degrees to ppm table could be a footnote or included somehow (though the drops column seems redundant)

Along with any info you think may be missing or incorrect

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