Ok but can't u change ph? what is kh? also I can't get my water tested for awhile but i still will.
I answered this in your other thread, but will do so here too. The following is cut/pasted from an article I wrote a few years back but it will explain things in simple terms. Water chemistry is a very complex subject but we as aquarists only need to recognize the basics.
Water hardness is the measure of dissolved mineral salts in the water, a portion of the TDS (total dissolved solids). There are two basic types of hardness of importance to aquarists, termed general hardness (abbreviated GH) and carbonate hardness (abbreviated KH, from the German “karbon” [carbon]). The combined GH and KH is sometimes termed “total hardness,” but this is of less importance because the GH and KH individually impact the water in different ways.
General Hardness is determined primarily by the minerals calcium and magnesium; GH is sometimes referred to as “permanent hardness” because it cannot be removed from water by boiling as can KH.
Carbonate hardness is the measure of carbonate and bicarbonate ions; carbonates and bicarbonates are the salts of carbonic acid. It is sometimes referred to as Alkalinity [not to be confused with alkaline as in pH, something very different]. KH is normally tied to the GH, since carbonate minerals include limestone, dolomite, calcium and calcite. Mollusc shells and coral are primarily calcium. Carbonate hardness is sometimes called “temporary hardness” because it can be removed from water by boiling which precipitates out the carbonates.
KH has some direct impact on fish; but it also “buffers” the pH by binding to additions of acids or bases, keeping the pH stable—or more correctly, preventing it from changing—and the higher the KH, the greater the buffering capacity. A simple way is to think of the buffer as a sponge that soaks up the acid being added; however, at some point it will become saturated, and further additions of the acid can then cause a sudden and very large fluctuation which is usually fatal to the fish. This buffering is why attempts to adjust (lower) the pH of hard water are dangerous and will fail unless the KH is first reduced.
pH stands for
pondus hydrogeni, Latin for “potential of hydrogen.” Water is made up of positively-charged hydrogen ions and negatively-charged hydroxyl ions, and pH is the measurement of the ratio of hydrogen and hydroxyl ions in a body of water. Acidic water contains more hydrogen ions, and basic (alkaline) water more hydroxyl ions; neutral water has an equal proportion. The pH is closely linked with the level of carbon dioxide (CO2) because CO2 produces carbonic acid. The hardness also impacts pH, since the carbonates bind to acids as they appear; as mentioned previously, this buffering will prevent or limit changes in pH.
Because each of the above impacts fish, it is important that the GH, KH and pH remains stable. This is another very involved topic I won't get into, the ways these impact fish. But selecting fish suited to your source water is always safer and easier on the fish and the aquarist because there is much less to "go wrong."
