Kryten / Fishme2death,
This is a piece I wrote for some-one else with questions about GH / KH etc. It's a bit basic but pick the bones for what you need.........
"Before explaining KH + GH it is probably best to understand that there is a third property that makes up the water chemistry triangle in a freshwater tank, this third property is pH. All three of these properties have an effect on our water chemistry.
pH is used to denote whether the water is acidic (pH reading below 7), neutral (pH reading of 7) or alkaline (pH reading of above 7). pH is fundamental in providing a good environment for our fish to live, all species have a pH range that they will be happiest in, therefore the more constant & stable we can keep the pH the happier our fish will be.
For the beginner is is probably easier to match our chosen species to the pH we have as opposed to trying to adjust pH to suit a specific species.
KH refers to the ability of our water to resist change in pH. This ability to resist change is known as carbonate hardness or more commonly buffering. Therefore when a KH reading is taken, the higher the KH reading the stronger the ability to resist changes / fluctuations in pH. A strong buffering capacity is beneficial if you have the pH that you require to keep the species of fish you are interested, however if your are trying to alter your pH for any reason a high KH reading is going to make it more difficult to effect this change.
Finally GH or General Hardiness, when water is referred to as hard or soft GH is the property being referred to. Water hardness is measured on two scales either DH (degree's hardness) or the chemical compound measured (CaCO3) in ppm (parts per million), both of these measurements can be used although most test kits will utilise the ppm measurement system. The two systems equate as:
0 - 4 dH or 0 - 70 ppm = very soft water
4 - 8 dH or 70 - 140 ppm = soft water
8 - 12 dH or 140 - 210 ppm = medium hard water
12 - 18 dH or 210 - 320 ppm = fairly hard water
18 - 30 dH or 320 - 530 ppm = hard water
As mentioned at the beginning all three of these properties are distinct, however it is important to realise that pH, KH & GH all interact, therefore any alteration to one will have an impact on the other two. Having said that with careful monitoring and control it is possible to make adjustments to these properties without having to rely on shop brought chemical additives such as pH Down.
For example to adjust the hardness of your water (GH) there natural additives that can be used:
Decrease GH (soften water) - Pure (100% organic) peat moss (no ferts or additives) or R/O water.
Increase GH (harden water) - Marble chips, coral, sea shells.
For all of the above (with the exception of RO water, which will be added a apart of water changes) the preferred method is to add a small amount the required medium to a small mesh bag & then place this bag in the filter box / cartridge. When using these for the first time it is advisable to add small amounts over a period of time whilst constantly monitoring all properties (don't forget adjustment to one of the properties will effect the other, in this case KH and then as a consequence possibly pH) until the desired level of GH is achieved."
Playing with the water chemistry is risky and I wouldn't recommend it unless you are experinced or it is really neccesary,
Hope that helps a bit......
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