Help me understand my hardness test results

[Last Triumph]

Hi all,

New member here - I'm in the middle of setting up and fishless cycling me freshwater aquarium and am getting to grips with the various elements of water chemistry, but am struggling to interpret the results from my hardness test, as the info in the supplied kit is confusing - either that or I'm being stupid...

The kit I have is this...

The instrutions for GH are pretty clear - I added 6 drops before the colour change which suggests 6 degrees German hardness, or 106.8 ppm - a fraction hard but pretty neutral if I understand correctly?

Where I'm struggling is with the KH results, where the colour changed at just over 5 drops - call it 5.5.

The instructions are not clear and can be found here... https://usa.hagen.com/File/53d811fe-d647-4353-b3dd-2205b995ee00

Leaflet page 5 details the KH test, however it mentions at the top of page 6 "Multiply the total number of drops by 10 to determine the general hardness in mg/L (ppm) as calcium carbonate (CaCO3)"

Why does it say general hardness when I'm testing for KH? Is this a miss print? Assuming not, does that mean that my KH is 55 ppm? If so, the kit suggests that is very low?

Does that correspond with my GH results of just over 100 ppm.

What is this telling me about my water?

Also, multiply by 20 for GH test and only 10 for KH test?

Sorry for all the questions, it's just the numbers and terminology in the instructions are confusing me and I don;t know if my water is now hard, sot or there is an unusual balance between GH and KH.

Anyone steer me in the correct direction?

Many thanks.

 

[stanleo]

I assume that you add one drop, shake and look at the color. When the color changes from one color to the other that is your hardness. If so, the number of drops it takes is your hardness in degrees. Don’t over think it. Just go by the degrees (number of drops). When researching fish, and the hardness required is in ppm, just divide by 17. That will give you the hardness is degrees. So a hardness of 100 ppm is just under 6 degrees. I always go by degrees cause that number is easier to remember. And the conversion is the same for GH and KH as far as I know.

With your hardness, you should be able to keep most fish except African lake cichlids and certain wild soft water fish.

 

[Last Triumph]

Thanks - I've just tested the tank water again (4 days after the measurement taken above) at only got 1 drop, meaning I've got issues as my PH has dropped from 7.5 to 6.5 - I think I need to add baking soda to add a buffer?
Would 5d KH be stable?
I'm looking to keep Ruby Bards, Harlequins, Dwarf Gourami, Chain loach, rummy nose tetras.

Much obliged.

 

[stanleo]

I just read those instructions and the conversion is wierd. With API test kits, the conversion for both is 17 but the procedure for testing is identical.

If I had your test, I would do their conversion. So your GH would be 6x20 which is 180ppm. KH is 6x10 which is 120ppm. The general hardness on the KH isn’t capitalized which might mean that it stands for something different. But I still say don’t over think it.

 

[stanleo]

When testing your tap water, you need to let it sit for 24 hours to outgas the CO2.

Your second test is probably more accurate but I would run the test again to make sure that you get the same results. With a KH of 1degree your pH will naturally drop however I suspect that if you let the tap sit for a day the pH would be closer to 6.5.

These numbers are fine for the fish you want however I would 86 the barbs. These fish can be aggressive if not in large groups and are known fin nippers. They might tear up the gourami.

 

[stanleo]

You can also get your hardness reading from your municipal water source website.

 

[Last Triumph]

Sorry, yes the readings just taken now are from the tank. Just tried them again and having now fully understood the instructions and conversion (I missed the conversion bit originally) my numbers are PH 6.5, KH 1, GH 6.
From my original test (of settled tank water) 4 days ago, the numbers were PH 7.5, KH3, GH6.

It looks as though my low KH has dropped further and caused a PH drop also. I've just added some baking soda to raise the KH to 5 for some PH stability. Hopefully that's the right thing to do? I've also got a fair few live plants to consider.

I hear you on the Ruby barbs - I thought they were the most peaceful of barbs?

 

[stanleo]

If there are no fish in the tank the baking soda won’t hurt anything but in the long term it won’t do anything useful either. You would have to use it every water change to keep the KH up and there really isn’t a need to do this for the fish you want. My KH is 1 and my pH stabilized at 6.4 and only goes up to 6.6 right after water changes. Fish can easily handle that. I think you would be fine.

I was confusing ruby barbs for tiger barbs. Seriously fish says they are generally peaceful but every fish is different to some degree and in my research years ago most barbs are highly active and can be aggressive. You could try them with caution. Sounds like a good mix of fish, well thought out.

 

[Byron]

First, reading the instructions you linked, there is an error in the numbers/text for KH (as you mentioned). I can't help with that, so let's move on.

The GH presumably was 6 drops and these may or may not be "degrees" as it doesn't say. It says to multiply the number by 20 to arrive at the GH in mg/l (same as ppm). That would be 120 ppm.

That's the test results. In the hobby there are two primary scales used, ppm (parts per million) which is the same as mg/l (milligrams per liter), and degrees (dH or dGH). You can convert between these with the number 17.9, multiplying degrees by 17.9 to obtain the equivalent ppm, or dividing ppm by 17.9 to obtain the equivalent dGH. Now, assuming the test result is correct, 120 divided by 17.9 equates to 6.7 dGH, which we normally round off to 7 dGH.

The KH following the instructions was 5 drops, multiplied by 10 to be 50 ppm. Same conversion here as for GH, so divide this by 17.9 and you have 2.7 or rounded up, 3 dKH. This assumes your test itself is correct and the instructions too, which as I said I cannot say, but let's assume they are. You could confirm these with your water authority. Just be sure to get their scale/unit, as some use other units from what we generally do (degrees or ppm).

Moving on, assuming GH is 7 and KH is 3, that is not unusual. While generally the KH will be close to the GH because minerals (calcium primarily) are involved in both, they can be quite different. You confirmation with the water authority will tell us if the test is or isn't reliable.

This is for tap water. Water in an aquarium with fish and plants or whatever may be slightly off, and if something in the aquarium is targeting the GH and/or KH (like calcareous rock or substrate) it may bee significantly different. So test the source water on its own so you/we know what you are starting with. Test the tank water alone and see if it is the same, close, or different.

I'll mention pH just so you know, as you should have this test kit on hand; it can be worth checking periodically or at any sign of problems. The pH is related to the GH and KH. Tap water may contain CO2 so out-gas this before testing pH. This is not needed for any other tap water testing, only pH; and it is not needed for aquarium water. Let a glass of tap water sit 24 hours, then test for pH.

Back to the GH and KH. You will have no issues with either for any of the fish mentioned. Avoid any species requiring harder water, which includes all livebearers, rift lake cichlids, some rainbowfish, and a few others. Soft water fish in general includes all characins (tetras, hatchetfish, pencilfish), rasboras, danios and barbs. Danios and barbs have somewhat more tolerance for slightly harder water, but that doesn't matter here. Gourami are soft water, cories are soft, loaches too. So no issues with GH/KH. The pH at 6.5 is good too, much better than above 7 for these fish.

Now to your concern about buffering...forget it. You have no need to buffer this water for soft water fish. Once you start adjusting water parameters, you can get involved and cause problems for the fish. What you want is a stable environment, meaning the GH/KH and pH tend to settle and remain with very little movement. The pH is the only parameter that may shift a bit, that's another topic. But provided you do not have calcareous substances to increase GH/KH, they will remain close to the source water. And regular (weekly) water changes of half the tank (I do about 60%) will work to maintain this stability. The second set of numbers, where the GH is remaining 6, the KH and pH have lowered, is ideal. I see nothing here to worry about.

Lots is written about "buffering" pH, but this is not always needed or advisable. If you had harder water species, you would have to increase the GH, raise the pH, and provide some form of buffering to maintain them. [By the way, baking soda is not a good buffering, for reasons I won't go into, but it is not advisable.] You don't for soft water fish with your water. I have zero GH and zero KH in my tap water and I add no minerals at all and I have tanks of wild caught soft water fish. The pH varies depending upon the tank, and I let it do what it wants. Some are around 6.5, others at 5 or more likely below that. Fish are fine because they are from such waters.

Last issue...I would not have any barbs in with gourami. All barbs are relatively speaking active fish, and sedate fish like gourami can be annoyed to the point of stress by active fish. However, dwarf gourami is a fish many of us do not advise; unless you know the source, by which I mean the breeder, not the store, they may carry the iridovirus which cannot be treated. We can talk about other gourami, like the Honey. Or you may want to forget gourami and go with more active shoaling fish. Rummynose are more active than some tetras, but quite peaceful.

 

[Last Triumph]

Thank you very much for your detailed reply.
My only concern was that if the tap water is PH 7.5 and settles in the tank to 6.5, that every water change might stress the fish as I'm reading that stability is the key?
I'm in the UK so don't have access to water authority numbers.

 

[Byron]

Thank you very much for your detailed reply.
My only concern was that if the tap water is PH 7.5 and settles in the tank to 6.5, that every water change might stress the fish as I'm reading that stability is the key?
I'm in the UK so don't have access to water authority numbers.

This pH is usually not an issue. Once an aquarium becomes established, it will develop a stability. Like I mentioned with the variation in pH between my tanks, which all have the same water changes, plant and fish load, etc, but each tank can have its own biological system. My tap water is 7.0 to 7.2, and I change 60% of a tank with pH 4-5 with no issues. Because the tank exerts its stability over the source water. If you had a much higher buffering (GH and KH), that would be a bit different.

Can you not contact the water people for GH and KH? Essjay knows a lot about this, she is in the UK too.

 

[stanleo]

Small Fluctuations in pH don’t harm fish, especially tank bred fish. If you change half the tank water at 6.5 with water that is 7.5 at most your pH in the tank will only rise by a couple tenths and there is no harm there. I have a similar situation and the tank is stable at 6.4.

And 17.9 is the conversion. Sorry about that.

 

[Last Triumph]

Out of interest, after adding some baking soda last night, I brought my KH back up to about 4.5dH.
I have just checked it 24 hours later and it was back down to 2 again.
Is it the ammonia levels causing the KH to reduce so quickly?
I've added more back up to 5dH and wonder what is causing the rapid KH reduction - a function of the cycle?
For information, Nitrites are beginning to show.

 

[Byron]

Out of interest, after adding some baking soda last night, I brought my KH back up to about 4.5dH.
I have just checked it 24 hours later and it was back down to 2 again.
Is it the ammonia levels causing the KH to reduce so quickly?
I've added more back up to 5dH and wonder what is causing the rapid KH reduction - a function of the cycle?
For information, Nitrites are beginning to show.

Baking soda is not going to do much as it is not a permanent buffer and organics will lower the KH. Better to not use it.

Why are you messing with the KH? I thought I had explained this previously. Ask me if anything was/is not clear.

 

[Last Triumph]

Sorry, my bad - I meant bicarb soda, not baking soda.
I was just curious why it keeps dropping, as it was a sudden and extreme pH drop that caught me out 25 years ago when I last kept fish and knew even less than today.
I lost a load of fish due to me using rain water, thinking this was a good move - the pH plummeted to about 4 from memory, and the fish died.
Only when I took a water sample to my local fish store did they explain about buffering and the dangers of using water too soft.
I guess I've been a bit over sensitive about the risk of ph drop due to insufficient KH - old habits etc.