What Is The Ideal Kh & Gh?

[Bignose]

EDIT:: Your KH should be about 2. Are you sure your test kits are good?

This is just a rediculous statement. Firstly, water comes in all different "flavors" for lack of a better word. There is hard water and soft water, even these have different flavors. Hard water normally means that the mineral content is high, i.e. high GH, and typically high GH means a high KH. But it is not a requirement! There is water out there with very high GH but almost no KH. Same thing with soft water, usually low GH means low KH, but again it is not a requirement.

So, it is just meaningless to say water should be a certain KH. There is a wide variety of water out there.

Secondly, this is just a silly statement also since you don't put any units on your statement. Hardness of water is measured in both ppm and degrees. Degrees normally mean German degrees, but there are actually about 5 'degrees' defined.


Anyway, to the OP, there is no set correct value of what GH and KH should be. The fish will prefer to be in water that is as close as possilble to their original water. That said, most fish will adapt pretty easily to a wide variety of waters. This is where research into your particualar species of fish is needed to know whether the fish you want are easily adapatble and/or whether they will adapt to your water.

If your water really had KH's in the teens, and the units were supposed to be (German) degrees, then that water should be prertty stable. Even if it was 10+ ppm, that water should still be somewhat stable though it would require keeping an eye on it them. If the pH dropped that quickly, something is adding an awful lot of acid to your tank. Or, you may not be doing the tests correctly. Or the test kits may be bad. I would take a sample of your tank water and go to the LFS and ask them to give you all the water stats. Be sure to ask for numbers, not just if they are "good". Maybe you can watch them as they test to make sure you are performing your tests correctly, too.

Finally, back to the subject of "correct" KH, since you read the link The Wolf gave you, I assume you know that KH keeps the pH buffered, that is, keeps the pH constant. Pretty much this means that any KH over 0 is good, since that means the water still has some buffering capability. There is no "correct" number, other than it needs to be above zero. If the KH is zero, the water will have no buffering capability and the pH will fluctuate. Any KH>0 and the water can buffer.

I would stop adding chemicals to the tank, and do several large water changes to get as much of the chemicals out of there. I am talking like 3 to 5 50 to 75% water changes separated by a few hours each. Maybe 75% a night for 3-5 nights. 1) The new water will have some buffering cap\ability and replenish what you have been taking out. 2) So long as you match the temperature of the new water with the old tank water (close, doesn't have to be perfect +- 10 degrees Fahrenheit is fine) the fish will be fine. and 3) you wash all the additives you have been putting in there out.

Once you get back to that base, then we can talk about whether you even needed the chemicals in teh first place. Probably not, but maybe. Most of the long-time members here really prefer to keep the tank as empty of chemicals as possible, especially since chemicals can lead to bad consequences later on -- like algae or pH crashes like it seems like you have experienced.

 

[n3ont3tra]

EDIT:: Your KH should be about 2. Are you sure your test kits are good?



This is just a rediculous statement. Firstly, water comes in all different "flavors" for lack of a better word. There is hard water and soft water, even these have different flavors. Hard water normally means that the mineral content is high, i.e. high GH, and typically high GH means a high KH. But it is not a requirement! There is water out there with very high GH but almost no KH. Same thing with soft water, usually low GH means low KH, but again it is not a requirement.

By saying they're KH 'should' be 2, I meant that, according to the chart, it should be about 2 degrees, with the given PH.
I also agree on getting the chemicals out of the tank, they generally are not needed. However, I think 75% water changes are a bit much, I'd suggest 50% at the most, and if you do 50%, do it every other day. Just my suggestion though.

 

[Bignose]

n3, you are reading that chart wrong then. That chart does not tell you what KH you should have versus what pH. KH and pH are almost completely independent quantities. Yes, in general higher pH waters have higher GH and KH, but that is not always so. Just like I said above, there is high mineral content water with low carbonate hardness (high GH with low KH), there are waters out there with high pH and low or even zero KH. That water will start with a high pH but adding even a small amount of acid, like the end product of the cycle, will lower the pH quickly. Similarly, there is water out there with low GH, low pH, but high KH.

That chart is the result of some calculations and is provided so that you don't have to do the mathematics yourself every time. You take your current readings of pH and KH and look in the corresponding row and column, respectively and read off what your approximate mg/L of CO2. That chart does not tell you what pH corresponds to what KH, since they are almost completely independent quantities.

Also, there is no physical/physiological reason why "50% at the most" is the largest waterchange. In general, so long as you match the temperature, pH and hardness of the new water (again, not perfect, close) with the tank water, you can do as large of a waterchange as you want. Even 100%. The bacteria won't care, the fish won't care (they'll probably like the new water). You are really limited to as much water as you can handle, in terms of buckets/tubs whatever. In this case, since the pH and hardness is bouncing around from the chemicals, I would want to get those chemicals out as fast as possible. Matching the pH and hardness is going to be tough since they are bouncing around, but in general fish are pretty hardy (no really sensitive species from the posts above) and I'd match the temp and change as large a volume as I could handle to get back to the base level original tap water.

 

[n3ont3tra]

Okay... I think I was wrong on the chart then... what you say makes sense. I figured that you could sort of work backwards with the chart to get a preferred KH reading. I understand now though. I was wrong... so Dr. Bogger and anybody else that reads this that I've confused, I'm sorry.

For the water changes, you probably could do as large a water change as you wanted, but the problem is, at least for me, that my tap water PH and tank water PH don't match, they are at least .5 (ppm??) off. So I do smaller water changes a little more often. Also, when you empty the tank, doesn't just having less water for them to swim around cause stress on the fish, like if you would do a 75% wc?

 

[Bignose]

Okay... I think I was wrong on the chart then... what you say makes sense. I figured that you could sort of work backwards with the chart to get a preferred KH reading. I understand now though. I was wrong... so Dr. Bogger and anybody else that reads this that I've confused, I'm sorry.

For the water changes, you probably could do as large a water change as you wanted, but the problem is, at least for me, that my tap water PH and tank water PH don't match, they are at least .5 (ppm??) off. So I do smaller water changes a little more often. Also, when you empty the tank, doesn't just having less water for them to swim around cause stress on the fish, like if you would do a 75% wc?

n3, pH is not measured in ppm. pH is measured in pH units. That is because pH is actually a logarithm of a concentration, and the units do not get along along when you perform the logarithm operation. So, it would be correct to say that your tap water and your tank water has a difference of 0.5 pH units.

Now, that said, a difference of 0.5 pH units is pretty small, so I would not worry about that. And, I agree that some fish can become stressed in a small amount of water, though there is stress also from being in a tank full of chemicals and in a tank with a fluctuating pH. It is a judgement call. Both sides can be argued from valid points of view. I stated my case above, and what you said is right too, sometimes there aren't clear cut 100% right answers.