water

A simple test to determine chemicals dissolved in water that might be harmful to organisms is pH. The percentage of free hydrogen (H% ) and a hydroxy ion (OH%) determines the pH of the liquid. Pure water (HOH) is made up one part hydrogen and one part hydroxy and given a neutral standing or a "7." If you have more hydrogen than hydroxy it is an acidic solution. If the hydroxy ions, are greater than the hydrogen ions you have a basic or alkaline solution. The concentration of the hydrogen ions [H+] in a solution determines the pH.

A pH of 6.0 to 9.0 is the range that fishes and invertebrates can successfully survive. Each species has its own tolerance level. The table below gives some special effects of pH on fish and aquatic life.

Minimum	Maximum	Effects
3.8	10.0	Fish eggs could be hatched, but deformed young are often produced
4.0	10.1	Limits for the most resistant fish species
4.1	9.5	Range tolerated by trout
	4.3	Carp die in five days
4.5	9.0	Trout eggs and larvae develop normally
4.6	9.5	Limits for perch
	5.0	Limits for stickleback fish
5.0	9.0	Tolerable range for most fish
	8.7	Upper limit for good fishing waters
5.4	11.4	Fish avoid waters beyond these limits
6.0	7.2	Optimum (best) range for fish eggs
	1.0	Mosquito larvae are destroyed at this pH value
3.3	11	Mosquito larvae live within this range