What is pH for an aquarium?

In chemistry, pH is a measure of the acidicy or basicity of an aqueous solution. pH is measured in numbers from 1 to 14. Seven is nuteral. Water less than seven is acidic, and water above seven is alkaline. pH measurements are important in medicine, biology, chemistry, food sciences, environmental sciences, oceanogrophy, civil engineering and more. Most of the Earth's freshwater surface bodies are slightly acidic due to the abundance and absorption of carbon dioxide.

Many Fish species eed a specific pH. Some Fish prefer water pH low, as in 5.5, or high, as in 8.f for them to be happy. Most fish species can tolerate a wide range of pH. Before you buy a fish you should always know the ranges it can tolerate and if it needs specific pH. A nuteral pH is always good, and make sure to avoid extremes.

Only experts with a wide range of chemistry should attempt chemically changing their pH. Before you adjust your pH, you should always have a reasonalble reason for doing so. It is also useful to know the pH of your tap water, or another source to determine if the fish you will keep can use that.  

Safely lowering pH: You can add a piece of wood to the tank, or put peat in your filtration system to slowly and safely lower the pH in your aquarium. But, sometimes theese substances can turn your tank yellow for a few years. Rmember that this does not lower pH overnight, but will introduce agents to keep the water a pH that you like.

Safely making pH higher: To safely and slowly make pH higer, add a seashell or a coral skeleton to your tank. Or you can put crushed coral in your filtration system. Rmember that this does not lower pH overnight, but will introduce agents to keep the water a pH that you like.

Chemically changing pH: Make sure your water does not contain any pH buffers before you attempt this... To chemically lower your pH add an acid to your water Adding more acids make the pH go even lower. Only do this when doing a water change. Sudden or Drastic changes in pH is very harmful and can kill fish. Remember chemically changing pH takes alot of research and you shouldnot attempt it based on just this or not having a chemical backround. Safely changing water pH will work for a novice, though.