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Hilariously high KH

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After a discussion here about crushed coral, pH buffering, and KH ramping, I decided to go buy a KH parameter kit (i'm slowly collecting these things, fun!).   My tank is heavily planted, and has about 60 fish of 7 species and 13 or so shrimp of 3 species.  It's a low-tech dirted tank with a UGF inset in 20% of the tank bottom.  Everything is thriving now.   pH is around 7.5, CO2 is surprisingly bouncing between 12 and 20 ppm despite no CO2 injection (I have rotting woodchips in my heavily organic substrate).  

And now... the drumroll please....  KH if I may have your envelope...    


KH is 16.  

So the really funny thing is, I went and checked my tapwater too.  We used cold water straight from the tap to fill this tank (no chlorine thank you wonderful home country!) and I knew it was hard because it hates my coffee machine.  But I also have a lot of gardening lime and a small amount of seashells + chalk-bearing flint rocks in the tank.   So I had to look...

Drumroll please....

Tapwater KH, if I may have YOUR envelope....


LOL my tapwater KH is 18.    Yes, I was very careful with the dropper and the volume measurements, as well as rinsing everything before hand in the liquid to be measured.   I might repeat the titration with a proper uL-precise lab pipette, but I am fairly confident the measurements are relatively accurate.  

So my tank, if its true, has actually lowered the KH a little bit.  And my fish and plants seem pretty happy now!   I might need to build a cichlid tank...

Anyhow, the adventure continues.  I'm happy to hear any comments or concerns.  I am admittedly new to this.  And yes, I will keep an eye on the KH and see how stable it is.  

Edited by daggaz
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my tap is 18 to 20 dKH too. 

Probably plants are not a huge fan? but otherwise it is fine. I heard it might be an issue for egg hatching but standard tap water breeding fish like my bristlenoses never have any issues


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The first thing that comes to mind with high kh low ph is you could have a not carbonate buffering system like phosphate for example can buffer water to but if memory serves won’t effect ph that much it would end up in the mid to high 7s 

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