# water hardness



## Dissidify (Apr 27, 2011)

i dont really understand how to controll the water hardness, or even how to measure it. need help!


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## Cat696 (Apr 27, 2011)

GH and KH tests will expain it, and measure it for you. That is your starting point. Ask when you need more help.. but don't forget to read!! It's boring, but you will be grateful that you did!! Good luck!!


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## jrman83 (Jul 9, 2010)

I kept fish for years without ever testing for hardness....unless you have especially tough fish to keep or you're tank is planted, in most cases it's not something you need to worry about.


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## NeonShark666 (Dec 13, 2010)

Hardness is the result of water being in contact with limestone at some time in its life. Livebearers, Rift Valley Cichlids and Saltwater fishes like it; most other fishes don't. Most water in the USA is hard, except for the Pacific Northwest. The easiest way to reduce hardness is with water changes, using RO or Distilled water.


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## rtbob (Jul 18, 2010)

Water hardness is measured using a general hardness or GH test kit.

It is the measurement of mainly dissolved calcium and magnesium ions. When fish are said to prefer "soft or hard" water it is GH that is being talked about, not carbonate hardness or KH.

Calcium and magnesium are very important minerals for maintaining a proper internal osmotic process for fish. These minerals are used up over time and must be replenished.
Water changes accomplish this in most cases.

KH is the capacity of water to neutralize acids. Water with a low KH is subject to PH crash. A KH of 50ppm or greater is desired to buffer the PH against wild swings to the acidic side of the PH scale. 

I went months without testing GH/KH and only recently bought a kit. As was stated most of the water here in the USA has a high enough GH/KH so it isn't a problem.

Where one would run into a problem is if you use Reverse Osmosis (RO) or Distilled (DI)
with out mixing with water that has the necessary minerals your fish need.

RO/DI water has been stripped of all the minerals necessary to maintain a stable PH and osmotic balance. It should be mixed with your tap water to reduce GH/KH for some species like Discus or other fish that thrive in a soft water/ low PH environment.

As stated by Jrman hardness is something you don't need to worry a lot about. If your like me and you just have to know what your levels are an API liquid GH/KH test kit can be purchased for $6.99 from the Foster and Smith website.


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## Gizmo (Dec 6, 2010)

rtbob said:


> Water hardness is measured using a general hardness or GH test kit.
> 
> It is the measurement of mainly dissolved calcium and magnesium ions. When fish are said to prefer "soft or hard" water it is GH that is being talked about, not carbonate hardness or KH.
> 
> ...


+5

GH is the hardness, or mineral content of your water, mainly trace elements like calcium and magnesium as mentioned above. If your city water utility gets its water from wells or mountain snow runoff like mine does, it will have medium-high hardness out of the tap. KH is a measure of the dissolved carbonate ions in your water, mainly carbonate, bicarbonate and carbon dioxide. KH is usually referred to as the alkaline buffering capacity, or just alkalinity, of you water, as higher KH reduces the tendency of pH to shift. On that note, pH is a measure of hydronium ions in the water, and generally refers to the acidity/basic level of your water. Most common tropical community fish prefer a hardness and alkalinity of about 5-8 degrees each, and a pH between 6.5 and 7.5. Many other fish like cichlids, discus, and marine fish prefer other variations on these.

Source:
Properly Maintaining the pH in a Freshwater Aquarium - Rate My Fish Tank


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