# KH and GH good range?



## zachary908

Hey, all.

I was wondering what a good KH and GH range is for optimal plant growth.

Plants such as Ludwigias, Synogonathus, erios, etc.

Also, what is a good product to raise KH?

I'll be using RO water.


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## somewhatshocked

Baking soda will raise KH. 

I've (fortunately, I guess) never had a plant that didn't thrive in my setups regardless of hardness. With the exception of UG, of course, which does best for me in water that's rather hard.


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## Diana

Most aquatic plants will handle a very wide range of both hardnesses. I would say the most forgiving plants are fine from either/both values being anywhere from about 3 German degrees of hardness on up and probably over 20 degrees. 

There are a few plants that are more particular. 
Some really only thrive in very soft water. Not pure RO, though. Even these extreme soft water plants need a little bit of minerals in the water. 
Some really only thrive in harder water. I have had problems with Hornwort in soft water tanks. Valisneria can use KH as a source of carbon, and requires water that is a bit higher in KH. It does not need much, though most Vals will also thrive in very hard water. 
Some plants have trouble when the Ca level is too low, so these plants would thrive in a tank with a higher GH. 

I would aim to keep the GH in the right range for the fish you want to keep. 
Next keep the KH roughly equal to the GH. 
Once these parameters are decided on, research the plants that suit these conditions. Unless you are at the extreme end of the scale (extremely soft or really hard) you ought to be able to keep probably 90% of the common aquatic plants.

I just checked the plant guide here at TPT. It shows pH, not GH or KH. pH is sort of linked to hardness, but the connection is not exact.
VERY ROUGHLY:
pH under 6 is very soft water, very specialized plants. GH and KH usually under 3 degrees
pH from 6 to 6.5 is usually a bit too soft for hard water plants. GH and KH usually 3-5 degrees
pH from 6.5-7.5 is mid-range, and GH and KH from 5 to 9 is probably fine for these plants. 
pH 7.5-8 might be too hard for the specialize soft water plants. GH and KH usually 9-20 degrees
pH over 8 is usually very hard water. GH and KH over 20 degrees. 

The Baensch Aquarium Atlas series has more detailed plant info, so If you want to look into some of the more unusual plants, a bit of research would be a good idea.


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## jgb77

I just wanted to point out certain plants,Toninas and Syngonanthus specifically, do not like baking soda at all. You can try adding some tap to your RO, or just use pure RO and add a bit of GH booster. 
Most plants do better in softer water anyways, by softer I mean KH, GH really doesn't matter in my experience as long as it's not super hard. A good range for the above plants sp. is KH as low as you want, but maybe 1-3 deg. and GH anywhere from 3-5+. Some of the nicest plants I've grown were in RO with no KH added and GH of 3.5 deg.
John


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## zachary908

jgb77 said:


> I just wanted to point out certain plants,Toninas and Syngonanthus specifically, do not like baking soda at all. You can try adding some tap to your RO, or just use pure RO and add a bit of GH booster.
> Most plants do better in softer water anyways, by softer I mean KH, GH really doesn't matter in my experience as long as it's not super hard. A good range for the above plants sp. is KH as low as you want, but maybe 1-3 deg. and GH anywhere from 3-5+.
> John


Thanks, John! Now that is the info I wanted. That gives me some numbers to shoot for. What do you recommend for upping KH if using tap isn't an option?


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## jgb77

Honestly, nothing. You don't need any KH and the plants you mentioned above do very well without any added back to the RO. 
John


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## zachary908

Fantastic. Thanks again.


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## slowride

Great info!!!


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## aquadoc

be careful though, too low of a kH can lead to trouble with pH swings. I shoot for a 4-5 kH as a nice middle ground for fish, plants and preventing frequent pH swings. That beings said, i also agree try to shoot for the same number for water hardness, 4-5.


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## zachary908

aquadoc said:


> be careful though, too low of a kH can lead to trouble with pH swings. I shoot for a 4-5 kH as a nice middle ground for fish, plants and preventing frequent pH swings. That beings said, i also agree try to shoot for the same number for water hardness, 4-5.


Aquadoc, what do you use to raise your kH?


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## Diana

I use baking soda, which is bicarbonate of soda. There are other carbonate/bicarbonate sources that do not include sodium, it might take a little searching, but they are available. 

One of the easiest is sand or fine gravel from limestone. This is calcium and magnesium carbonates, and will raise the GH and KH. Coral sand or Oystershell grit (sold for caged birds) may also help. Put any of these in a bag (nylon stocking) in the filter. If the difference is extreme, then prep the water before a water change so the GH and KH match the tank. When you are working with the most delicate of plants that really demand that soft water just a degree or so is enough. For most aquarium plants the actual number is not important, they can thrive in anything from soft to hard water. Just keep it stable for the fish, and so you know that your test results are reliable from one test day to another.


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## nonconductive

zach i never messed with KH when i was using straight r/o and everything did fine, and never had a ph swing. i'm sure our water is pretty similar since you're so close.


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## happi

nonconductive said:


> zach i never messed with KH when i was using straight r/o and everything did fine, and never had a ph swing. i'm sure our water is pretty similar since you're so close.


+1 

i have 0 KH and never had any issue with fish. aim for gh around 3-4dh, Ca around 30ppm and Mg around 8. 

dose less nitrate when using low GH, otherwise stunting is possible. now i don't want to hear if someone comes here and says it doesn't matter.


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## Hoppy

Low KH doesn't lead to pH swings, unless the KH is virtually zero. For sure a KH of 1 degree will prevent pH swings. Low KH does give you lower pH, because the CO2 in the atmosphere is absorbed by the tank water, and that lowers the pH a bit. The higher the KH, the higher the pH. But, for buffering against unstable pH, you don't need more that 1 degree of KH, and even less is still enough.


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## e-pirat

Don't forget that pH buffer is a sum of many other things besides HCO3 and CO3 anions. Plants takes nothing from carbonate hardness, at least they have CO2 as much as they need. And humic acids will provide pH buffer. So, having RO water as a water source there is no need to keep dKH level high only because you afraid of pH drops, 1-2 dKH will do.
P.S. Using NaHCO3 as buffer source is basically a bad idea because of Ni ions. Use KHCO3 instead, it will provide supplementary K, that is needed for plants growth.


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## aquadoc

zachary908 said:


> Aquadoc, what do you use to raise your kH?


API Buffer Max. My tap water is about a 1-2 kH. The directions do not give an amount to add to the tank to increase kH but i add only 1 scoop at a time/day then test (it comes with a scoop in the bottle). It usually takes me about only 2 scoops to get my kH up to 5 and i have a 65 gal tank.


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## brooklynfishman

SO IT does really matter then about GH? My KH is 4 and my GH is 8 or 9. Plants are growing well, but I always think there is room for improvement.

Do I need to lower my GH? Is there ANYWAY to do this other than RO and then adding booster?


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## wetworks

Adding a bit of crushed coral to your filter media will up both KH and GH as long as your pH in the tank is below 7.0. I have had KH-related pH crashes, but this was with a KH of 0. Added the crushed coral and voila! No more pH irregularities. I am sure that the KH was not the only possible cause, but the crushed coral did fix the problem. My tap water comes out with 0 KH and a GH of about 24 degrees. Never had any trouble due to GH though- at least that I know of. I do not frequently test the GH or KH these days though, because I have found that for the species of plants/fish/inverts I keep seem to really not care too much about TDS, GH or KH, except for possibly how they relate to the pH.


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## happi

brooklynfishman said:


> SO IT does really matter then about GH? My KH is 4 and my GH is 8 or 9. Plants are growing well, but I always think there is room for improvement.
> 
> Do I need to lower my GH? Is there ANYWAY to do this other than RO and then adding booster?


this is overall good parameter, no need to change anything.


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## Bryan Hearn

KH is important if you have fish.
That measures the minerals that they need in the water.
Crushed Coral is a better option than Baking Soda.


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## Greggz

Bryan Hearn said:


> KH is important if you have fish.
> That measures the minerals that they need in the water.
> Crushed Coral is a better option than Baking Soda.


You know you are responding to a post that is over six years old, right??:grin2:


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## madcrafted

Greggz said:


> You know you are responding to a post that is over six years old, right??:grin2:


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## Discusluv

Its okay, Ive done that before- consider the above posts as "hazing of the new guy". 
Welcome to the forum


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## Edward

Greggz said:


> You know you are responding to a post that is over six years old, right??:grin2:





madcrafted said:


>


That’s what the *SEARCH* button is for, isn’t it?


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## Discusluv

Edward said:


> That’s what the *SEARCH* button is for, isn’t it?


Really mocking and unnecessary.


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## Edward

Discusluv said:


> Really mocking and unnecessary.


 Discusluv,
I am not mocking anybody. Greggz’s and madcrafted’s posts above are hilariously funny and my comment about using the Search button is a compliment to Bryan Hearn for finding and continuing this thread instead of creating another one. 

I had been a moderator on APC forum for several years and our moderating team preference was to encourage members to use the search function in order to learn from and continue posting in the existing threads.


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## houseofcards

madcrafted said:


>


It wouldn't be difficult to use this to describe APC these days as well, sorry!


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## Discusluv

Edward, 
When you were a moderator did you welcome as well as offer guidance?
The new member hasn't been back- maybe direct your explanation toward this person. 
I dont need one.


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## RCB

Greetings, I'm browsing through the postings cause I'm a newbee and the hardness question is first on my list of many more questions for you experienced fish keepers. I'm not sure I understand the readings from the API GH&KH test kit. There is no color chart to compare color values and I could use some educating.

It took 8 drops of the GH solution before I noticed a color change. Does that mean I have a 143.2 GH hardness ? It took 3 drops of the KH solution until I noticed a color change. Does that mean I have a KH hardness of 53.7 ?


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## Discusluv

Hi @*RCB*, welcome!

I dont know much about your question, but Im sure @Greggz or @*Edward* would be happy to help you.


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## Wobblebonk

approximately 3 / 8 degrees aka 53 / 143 ppm ...


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## Greggz

RCB said:


> Greetings, I'm browsing through the postings cause I'm a newbee and the hardness question is first on my list of many more questions for you experienced fish keepers. I'm not sure I understand the readings from the API GH&KH test kit. There is no color chart to compare color values and I could use some educating.
> 
> It took 8 drops of the GH solution before I noticed a color change. Does that mean I have a 143.2 GH hardness ? It took 3 drops of the KH solution until I noticed a color change. Does that mean I have a KH hardness of 53.7 ?


It means you have KH 3 and GH 8. In general, these are good numbers.

Since GH is basically a combination of Ca & Mg, it doesn't tell you how much you have of each, or in what ratio. You may or may or not care, depends on your goals. 

And if you are looking for help, my advice would be to start a thread with all the information on your tank, including pictures. Focusing on one aspect at a time is not really very helpful. 

You need to look at the tank as a whole and consider what your goals are. Once you define your goals, I would spend some time seeking out tank journals that have similar set ups. Many here do a great job of documenting their journey, and to me it would be a very good place to start.

When I got started, I read some long journals over and over. Not that everything someone else does will work in your tank, but it will provide you a framework to get started.

Good luck and look forward to hearing more about your plans.


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## RCB

Greetings again and much obliged for the replies. I think , ( ??? ) I may be understanding the GH & KH numbers but I'm not 100 % sure. I'm using the API GH & KH Test Kit and perhaps I'm reading too much into the results but I do want to learn and understand what numbers mean. According to this " kit " you add up the number of drops it takes until a color change is noticed. After each drop, you cap the test tube and shake it....then repeat the process until you do notice a color change.


So; for the last week I'm daily checking the PH and Ammonia and the Nitrate.....etc as well as the GH & KH. The GH test takes 6 drops of their solution until a color change is noticed. Reading API " GH & KH Conversion Chart " the 6 drops equal 107.4. The KH test takes 4 drops of their solution until a color change is noticed. Reading API " GH & KH Conversion Chart " the 4 drops equal 71.6.


Greggz, I am just starting a few tanks after many many many Moons out of the hobby. I have a few original Meta-Frame tanks, original light fixtures and lids. Their whats called show tanks where their 24" wide, 6 " deep and 12" tall. Ive dug out all the old " tar " and replaced it with Aqueon sealant. Ive tested them over and over at different water levels and they don't leak. Ive set one of them up with the necessary elements, heater..filter..LED bulbs..thermometer..2 1/2 " of sloped gravel. Its got some nice Congo Wood which Ive boiled over and over and it stays put. Some Crypts and Java Moss and Lilaopsis are doing well.


30 years ago I had a few 40 gallon tanks and a few 20 gallons....all Meta-Frames. I recently decided to get back into the hobby by pulling out from storage, a few of the smaller tanks.I'm an old geezer and don't have a camera or a fancy newfangled smart phone ( I want neither ). Heck, LED lights weren't even around when I was in the Hobby ( I purchased a Finnex Fixture and a CO2 system for the 20 gallon tank. That tank is a loooooong way from being set up, but I'm thinking ahead .


Thanks to all who share their acquired knowledge as it is a real pleasure reading through and learning from the various postings.


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## Greggz

RCB said:


> Heck, LED lights weren't even around when I was in the Hobby ( I purchased a Finnex Fixture and a CO2 system for the 20 gallon tank. That tank is a loooooong way from being set up, but I'm thinking ahead .


What are these LED lights you speak of???:grin2::grin2:

Just kidding, but you know there are a number of us old geezers who are still using good old T5.

Now that is an entirely different discussion, and one that still comes up here often.

Good luck and welcome back to the hobby.


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## Wobblebonk

Each drop represents 1 degree of general hardness/karbonate hardness or 1 degree german hardness.
1 degree is equivalent to 17.848 ppm. Generally people report the degrees and not the ppm, but yes 6 degrees is roughly 107.4 ppm.

6 drops means somewhere between 5 and 6 degrees, usually there's no need to make it so precise as to figure out it's actually 5.87 degrees or the exact ppm but to do this you would basically use 10ml (or more) and then each drop is .5 degrees (or .25 etc.)


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## RCB

Wobblebonk said:


> Each drop represents 1 degree of general hardness/karbonate hardness or 1 degree german hardness.
> 1 degree is equivalent to 17.848 ppm. Generally people report the degrees and not the ppm, but yes 6 degrees is roughly 107.4 ppm.
> 
> 6 drops means somewhere between 5 and 6 degrees, usually there's no need to make it so precise as to figure out it's actually 5.87 degrees or the exact ppm but to do this you would basically use 10ml (or more) and then each drop is .5 degrees (or .25 etc.)



Greetings 2U Wobblebonk, That there was the EEEEE-ZAK and PREEEEE-SISE kinda answer this geezer needed to understand the reason for the PPM and the degrees. Thanks for educating me.


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## Jeff5614

houseofcards said:


> It wouldn't be difficult to use this to describe APC these days as well, sorry!


I remember when APC seemed to have more traffic than TPT. Ahhh, those were the days.....


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## Tyrant46290

Just throwing this out there.....
I have a tank setup with about 18 types of the more common plants. They are all doing great and spreading out.
Ph 7.4
Gh 7
KH 13
Temp 78°
Medium to high flow
1-2 watts per gallon ish.....LEDs


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