Water Quality Testing

Aquatic Science 2011

pH• The concentration of hydrogen ions (H+) in the

water• High hydrogen ion concentration means the

pH is low (acidic) and a low H+ concentration means the pH is high (basic)

• Fish can live in pH ranges from 6.0 to 9.0, but their quality of life is bestbetween a pH range of 7.0 and 8.0

Dissolved Oxygen - DO

• Fish depend on DO to breathe• Too many fish will require more oxygen than

is available in the water. • Fish waste, decaying food, and rotting plants

are all consumed by bacteria, which also require oxygen.

• Amount of DO in water depends on temperature

Can You Guess?

***Start at arrows on the left side

Alkalinity - kH

• Alkalinity in aquariums is measured by the concentration of carbonates and bicarbonates in the water.

• Acts as a buffer– Helps resist changes in pH

• This is also referred to as "carbonate hardness" or kH

• Low alkalinity can allow pH to fluctuate

gH – General Hardness

• General hardness (also known as permanent hardness or gH) is the measure of the total minerals dissolved in the water, mainly calcium and magnesium salts.

• Hard water has high concentrations of calcium and magnesium, while the opposite is true of soft water.

General Hardness• The concentration of ions is important for the

transport of nutrients across cell membranes and can affect reproduction and egg fertility

• A freshwater planted aquarium may require soft water with a low general hardness in the range of 3-5 dH. Conversely, an African Cichlid aquarium requires water with a higher general hardness range of 10-15 dH.

Temperature• Tropical fish thrive in a very narrow

temperature range, most often 72-78F.• Temperatures even slightly above or below

this range will stress fish over time and could lead to disease.

• Rapid changes in temperature should definitely be avoided. Few things kill fish faster than a rapid temperature change.

Ammonia• Extremely toxic to aquatic life• Some portion of all nutrient inputs (the

proteins, carbohydrates, and fats in fish food primarily) ultimately end up as ammonia.

• Excess ammonia:– Damage to the gills.– Impaired respiration (breathing)– Damage to skin, fins and the intestine

Ammonia Toxicity

• What to Watch For– Gasping/ impaired respiration – Abnormal swimming/whirling– Bloody areas on the body– Increased mucus production– Bloody areas in the intestine– Acute death

Nitrate/Nitrite

• Nitrite binds to red blood cells and blocks their ability to transport oxygen

• Affected fish may gasp at the surface or stay near airlines or water inflow

• Nitrates are not as toxic, 50 ppm is an acceptable level for ponds, freshwater community

• Levels can normally be maintained by performing weekly water changes of 10% or biweekly water changes of 20%.