Explain GH/KH

I tested my GH/KH in my tanks and the results were:

2 drops in my 75 and 25

35.8 ppm GH/KH
2°dKH

PH = 6.2-6.5


4 drops in my 10 (shells added in filter and substrate for my cray)

71.6 ppm GH/KH
4°dKH

Ph= 7.5-7.8


What does this mean other than simply the water with shells is harder. Can anyone tell me what it means in overall tank health. I read that Rams like soft water and low ph so I'm assuming that my gh/KH being low is good for them. But what about my 75 that houses acaras and other cichlids

 

I'm no expert, but the way it was explained to me, is that hard water fish don't do well in softer water due to lack of minerals. Soft water fish can adapt fine to hard water in most cases as they can take what minerals they need, and simply not intake the extra. However harder water is tricky when it comes to fish breeding as some fish need soft water to breed.

If I remember correctly, GH is the amount of dissolved minerals in the water, KH is the amount of dissolved carbon in the water. I know they can effect PH and vice versa, but I'm not versed in that sense.

 

I'm no expert, but the way it was explained to me, is that hard water fish don't do well in softer water due to lack of minerals. Soft water fish can adapt fine to hard water in most cases as they can take what minerals they need, and simply not intake the extra. However harder water is tricky when it comes to fish breeding as some fish need soft water to breed.

If I remember correctly, GH is the amount of dissolved minerals in the water, KH is the amount of dissolved carbon in the water. I know they can effect PH and vice versa, but I'm not versed in that sense.

That makes me think I should add shells to each filter but I don't want the high PH in my other tanks

 

You should have a separate test for gH and kH. kH which is carbonate hardness, which is your water's buffering ability (i.e. the ability for the water to resist pH changes). gH which is general hardness is the amount of dissolved magnesium and calcium in your water which directly relates to pH. But regardless your water has either a low gH, low kH or low gH and kH

Heres a link that may be helpful:

 

You should have a separate test for gH and kH. kH which is carbonate hardness, which is your water's buffering ability (i.e. the ability for the water to resist pH changes). gH which is general hardness is the amount of dissolved magnesium and calcium in your water which directly relates to pH. But regardless your water has either a low gH, low kH or low gH and kH

Heres a link that may be helpful:

I do have separate tests and the drop numbers were the same. For both and there is only one listing on the table for both so I assume it means they happen to be the same?


It was 2 drops on the GH bottle and 2 drops on the KH bottle for my no shell tanks and 4 drops on the GH and 4 drops on the KH for the shelled tank.

Am I reading it right?

 

Don't know how to add a pic to that last post so here is the chart

 

jdhef that article was super helpful. I'll be adding some baking soda and an airstone to increase my KH

 

Cichlids in general prefer hard water. Maybe it depends where they come from but Bluestreakfl is right that softwater fish adapt much better to hard water than vice versa. I put my GH up to about 6dGh and my ph is 8.3 because my KH is off the charts and all the fish in my signature are doing great, including the Rams

I would add the coral with your KH which is a bit too low and would be unfortunate if your PH dropped below 6.0. It won't take much coral to raise it all a bit. Its easier than constantly using baking soda.

 

Cichlids in general prefer hard water. Maybe it depends where they come from but Bluestreakfl is right that softwater fish adapt much better to hard water than vice versa. I put my GH up to about 6dGh and my ph is 8.3 because my KH is off the charts and all the fish in my signature are doing great, including the Rams

I would add the coral with your KH which is a bit too low and would be unfortunate if your PH dropped below 6.0. It won't take much coral to raise it all a bit. Its easier than constantly using baking soda.

So just a little coral in the filter media compartment? I put shells in my 10 gal and the ph shot up to nearly 8. I need around 6.5.

 

The biggest thing with PH is stability. Fish can adapt to stable PH of any safe range for the most part, however swings is where you have issues.

 

Yeah, anytime you raise KH you raise PH. Rams are fine in a variety of water conditions from soft to medium hard water. Medium hard water would automatically have a higher ph.

The other thing you could do is use Seachems Neutral regulator or buffer which will raise and hold steady your KH. You might have more control over your numbers that way. You can use Replenish also to raise your GH to the medium soft range. All fish need some minerals for osmotic regulation and overall health.

 

Yeah, anytime you raise KH you raise PH. Rams are fine in a variety of water conditions from soft to medium hard water. Medium hard water would automatically have a higher ph.

The other thing you could do is use Seachems Neutral regulator or buffer which will raise and hold steady your KH. You might have more control over your numbers that way. You can use Replenish also to raise your GH to the medium soft range. All fish need some minerals for osmotic regulation and overall health.

Is there a specific type of coral I should look for?

 

What type of cichlids do you have? Rams and acaras are both South American cichlids and prefer lower pH and hardness. As long as you keep up with water changes and watch the pH you should be fine without adding anything else. It is true a kH of 4-6 or higher leads to a more stable pH but water changes will replenish the water's buffering capacity and remove organic wastes that can use up the buffers and lead to a pH drop.

Depending on the other type of fish in the 75 a bag of crushed coral substrate can be added to the filter (similar to the shells you added in the 10). This is a typical substrate used in saltwater tanks and can be found at most pet stores.

 

Just crushed coral, I think you can buy this at the pet store? You can start with a couple tablespoons. It should raise GH and KH.

 

What type of cichlids do you have? Rams and acaras are both South American cichlids and prefer lower pH and hardness. As long as you keep up with water changes and watch the pH you should be fine without adding anything else. It is true a kH of 4-6 or higher leads to a more stable pH but water changes will replenish the water's buffering capacity and remove organic wastes that can use up the buffers and lead to a pH drop.

Depending on the other type of fish in the 75 a bag of crushed coral substrate can be added to the filter (similar to the shells you added in the 10). This is a typical substrate used in saltwater tanks and can be found at most pet stores.

Yeah everything I've read about Rams says they do better in soft water and low ph. Which is pretty much exactly what I have

The other tank has blue acaras, a convict, and soon a severum, along with some blackskirt tetras and cories

 

Is there a specific type of coral I should look for?

I bought crushed coral at PetSmart. Sadly, even though I only need about 1/2 cup, the smallest bag they had was 15 pounds, so I have a lifetime supply. It is actually sold as a substrate for salt water tanks, since salt water fish require a high pH

 

I think when you read stuff like that its how they are in the wild. Generations and generations of rams are bred in more neutral water. He is a breeders comments (just FYI):

 

I'm not understanding the whole GH and KH thing.
Bought a kit and tested my cycling tank and tap water today.

Cycling tank (adding ammonia at 1ml daily)
GH- 5 drops = 89.5
KH- 3 drops = 53.7
pH=6.4
Ammonia=1ppm
Nitrites=2-5ppm
nitrates=20

Tap:
GH- 9 drops = 161.10
KH- 6 drops = 107.40
pH 7.4
ammonia, nittites, nitrates = 0

What does this all mean?? Thanks!!

 

I don't know much about GH and/or KH myself, but I thing both have to do with how hard or soft your water is. I was actually about to post my own thread with the same question myself just now.

Can someone with more knowledge answer please???!!!

 

I'm not understanding the whole GH and KH thing.
Bought a kit and tested my cycling tank and tap water today.

Cycling tank (adding ammonia at 1ml daily)
GH- 5 drops = 89.5
KH- 3 drops = 53.7
pH=6.4
Ammonia=1ppm
Nitrites=2-5ppm
nitrates=20

Tap:
GH- 9 drops = 161.10
KH- 6 drops = 107.40
pH 7.4
ammonia, nittites, nitrates = 0

What does this all mean?? Thanks!!

I'm not good at explaining but cycling will lower your kh&gh. When your tank is cycled regular water changes will keep the levels closer to the tap water values. Kh is carbonate hardness, sometimes refered to as alkalinity or your alkaline buffer which stabilizes pH.
If you need to raise kh during cycling to keep pH up until cycled you can use crushed coral(disolves slow, more stable) or epsom salts ( wears off quicker look fir fluctuations). Long term I would use the crushed coral.

Here is an article that may beeasier to understand than my redneck engineering. Lol

Sorry link didn't work, but I just googled gh&kh in aquariums.

 

gH is permanent hardness. kH is temporary hardness. kH is what buffers your pH, and is basically a measure of the calcium carbonate in your water. gH is essentially everything else that hardens your water.

It's possible your plants and/or cycling is lowering your kH, but it shouldn't have a drastic effect. Your water is weird LOL.

 

Gh is a measure of the amount of minerals of calcium and magnesium, which are bivalent cations, meaning they have two positive charges. Dissolved calcium carbonate (calcite) or magnesium sulphate (epsom salt) are two examples of minerals that contribute to GH. Water softeners that use salt remove these cations and replace them with sodium.


KH is a measure of total alkalinity, which in normal water is the sum of three basic types of alkalinity: carbonates, bicarbonates, and hydroxides. At your pH the vast majority of the alkalinity is in the form of bicarbonates. Two common examples of substances that contribute to KH are calcium carbonate (calcite) and baking soda (sodium bicarbonate). KH plays a central role in determining what your pH is going to be.


Notice that calcium carbonate contributes to both GH and KH. It is the most common mineral in water, from groundwater coming into contact with limestone. Since most of the GH and KH typically comes from calcium carbonate, most of us have GH and KH values that are not that far apart.

 

Goodness. I've had my current tanks running for more than a year now and I've never payed attention to GH or KH. I've kept track of the pH. Thanks for all the answers guys!

 

So what happens when I add crushed coral to my tank, how does that buffer the pH?

 

Crushed coral is made of calcium carbonate, which when it dissolves adds to both the GH and the KH. It dissolves very slowly as it reacts with some of the CO2 in the water, and should dissolve a little faster as the pH goes down. The carbonate part of the calcium carbonate is the buffer that works to hold the pH steady. If you use too much coral the pH will climb higher than you want it... the trick is to find the amount that counteracts the acid being produced by the biofilter.

 

Do you have to add anything to your tank if your pH is constant?

Psalm18.2, I hope it's ok that I butted into your thread to learn the answer to the same question! I'm really sorry. If you want, I can start my own thread to ask my questions.

 

NO that's fine. I don't mind.

 

NO that's fine. I don't mind.

Thanks! You're so nice

 

Do you have to add anything to your tank if your pH is constant?

In a tank with a functioning biofilter the KH is always going down. When it gets close to zero the pH can fall dramatically, but for most of us the tap water contains enough KH that you would have to go a long time without a water change before that happened, so nothing needs to be added to bolster the KH buffer. Those who have low KH tap water might need to add something. It really depends on how often you change water, and the bioload in the tank. You can get by with low KH water if you do frequent water changes, but a tank crowded with fish that gets new water (along with new KH) only once a week will need some added buffering to hold the pH steady for that length of time.

 

In a tank with a functioning biofilter the KH is always going down. When it gets close to zero the pH can fall dramatically, but for most of us the tap water contains enough KH that you would have to go a long time without a water change before that happened, so nothing needs to be added to bolster the KH buffer. Those who have low KH tap water might need to add something. It really depends on how often you change water, and the bioload in the tank. You can get by with low KH water if you do frequent water changes, but a tank crowded with fish that gets new water (along with new KH) only once a week will need some added buffering to hold the pH steady for that length of time.

Interesting. I've never realized that! Thanks for the info!

 

So I did a little test today on a hopefully newly cycled tank.
Ammonia 0
Nitrites 0
Nitrates 5
KH (3 drops) =0-.50 ppm
GH (6 drops)= 100-200ppm
pH either 5.5 or 6.8 (2 different tests)
temp 78.5 (using digital probe)

Using crushed coral in filter to buffer pH.

So basically what does all this mean?

 

There is a really good article here on Fishlore about the relationship between pH, GH and KH - have a look here. It does an amazing job explaining it.
It also explains how pH can shift, why, and how to fix it.

Hope that helps.

 

There is a really good article here on Fishlore about the relationship between pH, GH and KH - have a look here. It does an amazing job explaining it.
It also explains how pH can shift, why, and how to fix it.

Hope that helps.

Thank you, that was a good read, should be a sticky.

 

I'm glad you enjoyed it - he did a fantastic job explaining it. I'm glad it helped!