What affects fish more - kh or gh?

rwood
  • #1
Hey all,

Very much a beginner question - but a) What affects fish more - kh or gh

and b) I noticed on the fish profiles (on fishlore.com) it has the water hardness as degrees of dH the max being about 20 or so. However my testing kit goes up to 180 and when I test my tank with my kit it reads at around 140; I know that is very high however all my fish seem happy (tetras, kribs, corys, danio).

I have bought a 'pillow' which is supposed to reduce the gh by 70ppm each 40hrs. Is the 140 my kit is returning most likely a measurement of gh in ppm and if so what is the relationship between ppm and the degrees of dh that the fish profiles refer to.

Thanks!
 
Wolfgang8810
  • #2
I fond that the hardness of the water dosent really affect the fish. however when going form softer water to harder water you should acclimate very slowly because the difference makes it harder for fish to process oxygen (same with going from hard to soft). I have had 10 cardinal tetras in my tank forever and they prefer soft water and mine is very hard water and tey are thriving all of which I got around 3/4 of an inch and they are now over 2 inches so jsut take your time acclimating and don't really worry too much about it. kh affects fish more than ph IMO
 
rwood
  • Thread Starter
  • #3
Alright thanks for your help; I'm just more wondering exactly what all the measures mean so I can understand it. Also what is the difference between kh and gh and what effect do they have on a tank?
 
0morrokh
  • #4
If I understand it correctly, kh (carbonate hardness) is the buffering capacity of the water (it is not permanent and can be removed by boiling), while gh (general hardness) is dissolved ions and can't be changed except by mixing the water with water with a different gh. I think kh is more important to a tank because it keeps the pH stable. However most tap water already has a high enough kh and the only time you'd need to worry about it is if you have a planted tank and are dosing high CO2, which could cause the pH to crash if there's little buffering capacity (low kh) (but with most tap water this isn't a concern). As far as the fish go hardness doesn't matter at all unless you are trying to breed a very sensitive species (which may need a low gh).
 
rwood
  • Thread Starter
  • #5
So other the ph does that mean I really don't have to worry all that much about hardness?
 
Wolfgang8810
  • #6
you should know wat it is and take precautions when acclimating but other than that I realt don't pay too much attention to it. I'm sure other fishloreans would disagree but this is what I believe
 
rwood
  • Thread Starter
  • #7
yeah - I don't know if anyone is really reading this but I'm hoping someone may glance across it and have something more to offer. As surely gh must have *some* effect on your tank environment - plants, fish, whatever - I just want to know what it is
 
Wolfgang8810
  • #8
you could try starting a new thread and I promise I won't reply lol good luck
 
rwood
  • Thread Starter
  • #9
lol, don't stop replying; it'd be a very empty thread otherwise I might start a new one later - at work atm so I *probably* shouldn't be on
 
Wolfgang8810
  • #10
haha its late here I'm all the way on the other side of the world Florida
 
rwood
  • Thread Starter
  • #11
lol; just a bit of a time difference there
 
0morrokh
  • #12
So other the ph does that mean I really don't have to worry all that much about hardness?

I wouldn't worry about pH either.
Most Freshwater fish are already acclimated to your water since they were in similar water at the fish store and possibly the breeder too.
Stability is the most important thing...as long as your pH and hardness isn't fluctuating, your fish will be fine. PH does have more effect on some aquatic plants I think, but if you are keeping delicate plants you'll be using co2 which would lower the ph anyway, so no problems there.
 
rwood
  • Thread Starter
  • #13
Thanks for all your help everyone! I've had a chat onplant geek and they have told me I shouldn't lower the hardness in regards to my plants as the stuff that lowers the hardness hurts the plants and that hardness doesn't really affect the fish at all.
 
0morrokh
  • #14
True, chemicals that change pH or hardness almost always do more harm than good. Like I said before, it's stablity that matters, not the numbers.
 
darkwolf29a
  • #15
You can lower some of the parameters naturally with such things as driftwood and peat moss. I'm just starting to learn about peat myself, but I can tell you that driftwood will lower your hardness a bit. Now, understand, they aren't going to make a HUGE difference, but some is better than none, in some cases.

And, besides, driftwood is very cool for the fish to swim around, through, etc.
 
pistorta
  • #16
Regarding your measurements, one is measured in degrees the other in ppm or mg/L.

I would never suggest altering hardness or pH with chemicals, as they are short-term fixes. Not only are they short-term, but they will negatively affect your test results, through false readings, especially that of CO2. Regarding your other concerns, KH will have a huge impact on the stability of your pH when adding CO2. If your KH is high, you will have a tough time decreasing your pH, which may be necessary depending on the amount of CO2 you want dissolved in your water. Ideally, you should look at ~20 ppm.

My pH is naturally high and as a result, it is difficult to increase levels of CO2, even though I am overloading the reactor (undissolved CO2 is circulated through the use of a powerhead). As a result, I have begun to use RO water supplemented with baking soda (to increase the KH from 0) and have had a drastic improvement in the growth of the plants.

GH is not something I concern myself with as I am not involved in breeding which is where this will have a more crucial impact. As others have posted, fish can acclimate to different hardness levels of water...to an extent.
 

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