Gh/Kh

[Ruddy Roach]

I've read the "Whats in your water" pinned topic on this forum but I'm still not totally sure about it. I understand the Gh but I'm a little confused with the Kh. A little help please!

Thanks,

Andy

 

[Morrgan]

The KH is a measure of carbonates in the water. A high KH buffers the pH and stops it from fluctuating, which is a good thing. A low KH means the pH might drop suddenly even from small changes, which of course is bad for the fish. Some fish come from waters with a high KH (livebearers for example) and others from waters with a low KH (such as black water species).

To keep the pH stable, a KH of at least 2-3 (on the German scale of hardness, I hope someone else can change it into ppm if needed) is recommended. However, in one of my tanks the KH is only 1-2 and the pH stays stable thanks to frequent water changes and low stocking.

Hope this helps.

 

[Def]

Slight correction (or perhaps I'vemisunderstood your scale), KH should ideally be between 10 and 15 dKH. My KH is exceptionally low, I've found that even buffering it up to 7dKH provides a buffer against ph drops...

 

[LadyMinion]

Oddly enough, I've just been doing some research on this. I found an excellent article explaining the differences and how KH works here.

 

[Ruddy Roach]

Thanks a lot for the advice!

It's cleared a lot of questions up for me.

 

[Morrgan]

Slight correction (or perhaps I've misunderstood your scale), KH should ideally be between 10 and 15 dKH.

Ideally for who? It really depends on the fish. 10-15 dKH is ideal for for example Lake Tanganyika cichlids and livebearers, but is much too high for soft water fish.