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pH in Aquariums. Quick Review. Acids produce H + (also written as H 3 0 + ) ions in water Bases produce OH - ions in water H + + OH - → H 2 O An acid plus a base yields a salt and water. HCl + NaOH → H 2 O + NaCl. Neutral Water. Neutral water is given a pH value of 7.0.
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Quick Review • Acids produce H+ (also written as H30+) ions in water • Bases produce OH- ions in water • H+ + OH-→ H2O • An acid plus a base yields a salt and water. • HCl + NaOH → H2O + NaCl
Neutral Water • Neutral water is given a pH value of 7.0. • It contains equal amounts of hydrogen ions (H+) and hydroxide ions (OH-). • Dissolved chemicals and minerals change the balance of those ions from a perfectly neutral state.
Increase the amount of hydrogen ions (H+), and the water becomes more acid ("low pH"). • Increase the amount of hydroxide ions (OH-), and the water becomes more alkaline ("high pH"). • The further these values rise or fall, the more acid or alkaline the water becomes.
Acids • pH = 0 Battery Acid, Hydrofluoric Acid • pH = 1 Hydrochloric acid in the stomach • pH = 2 Lemon Juice, Vinegar • pH = 3 Grape fruit, orange juice, Soda • pH = 4 Acid rain, tomato Juice • pH = 5 Soft drinking water, black coffee • pH = 6 Urine, saliva • pH = 7 Pure water
Bases • pH = 7 Pure water • pH = 8 Sea water • pH = 9 Baking soda • pH = 10 Great Salt lake, Milk of Magnesia • pH = 11 Ammonia solution • pH = 12 Soapy water • pH = 13 Bleaches, Oven Cleaner • pH = 14 Drain Cleaner
There is no "normal" pH that applies to all fish. • Because fish originate in ponds, rivers, streams, lakes, and oceans that have different pH levels, their needs are different. • Saltwater fish prefer an alkaline pH of 8.0 or above. • Freshwater fish thrive in a range lower than that, somewhere between 5.5 and 7.5, depending on the specific species.
pH can change over time, and even change in the course of a day. • Typically it drops at night and rises during the daytime. • pH will change as new fish are added or removed, as water is added or changed, and as the biological processes change in the tank.
Preferred pH of Common Frewhater Fish * Angelfish 6.5 - 7.0* Clown Loach 6.0 - 6.5* Goldfish 7.0 - 7.5* Harlequin 6.0 - 6.5* Hachetfish 6.0 - 7.0* Neon Tetra 5.8 - 6.2* Plecostomus 5.0 - 7.0* Silver Dollar 6.0 - 7.0* Tiger Barb 6.0 - 6.5* Zebra Danio 6.5 - 7.0
pH as it relates to Aquariums • Acids are chemicals that lower the pH • Bases are chemicals that raise the pH • Buffers are chemicals that can 'tie up' acids or bases and keep the water at a specific pH. Different buffers will keep the pH at different values. • Different fish from different habitats have different pH requirements.
How Important is pH? • Changes in the pH, especially sudden changes, can prove harmful or even fatal to fish . • As the pH rises it increases the toxicity of chemicals such as ammonia. • It is an important factor to monitor during the break-in of a new tank. • pH changes are particularly hard on young and sick fish. • In a number of species of fish, breeding occurs only within a specific pH range.
Adding acids and bases can change the pH of your aquarium, but this can be dangerous. • Wood in the tank or peat in the filter can gradually lower pH. • Shells or coral can gradually raise it.