General Hardness (GH)
- Ideally range from 5-12 dH
- Measures all bivalent cations, majority is dissolved magnesium and calcium
- Measured in “dH” aka degree hardness— 1 dH=17.8ppm CaCO3
- Hardness of the water plays into the buffering ability of the water
- Hard water >300 mg/L, soft water <150 mg/L
- Used for skeletal and scale growth, and in mollusks and crustaceans for shells
- High levels can affect drugs administered in the water and require higher concentrations of drug be added
- Too high: zinc deficiency cataracts due to competition for absorption with calcium, nephrocalcinosis
- Too low—decreased buffering capacity causing acid pH in environment (see KH and pH information on each parameter), slow or stunted growth (due to not enough calcium for growth)
Carbonate Hardness (KH)
- Should be > 4.5 dH (degree of hardness), 7-9.8 dH in coral or invertebrate tanks
- Other terms used “buffering capacity”, “alkalinity”
- Measure of the carbonates and bicarbonates within the system
- Carbonates provide buffering capacity and an energy source for use by the bacteria involved with biofiltration and the plants in the tank when CO2 levels fall
- The higher the KH, the more buffering capacity of the water, the larger ability to bind H+ ions and resist pH drop in the water
- Important for corals and invertebrate skeleton
- If the buffering capacity is used up and not replaced or Hardness level <4.5 dH the everyday processes that occur in the tank with continue to drop the pH = biofilter will stop working, fish will become stress and undergo changes due to acidic irritation
- Treatment: Water changes with help replace the buffer, Limestone or baking soda can be added to provide buffer
Phosphate
- Phosphate levels <0.1 mg/L
- In high levels will cause algal over growth
- Naturally occur due to breakdown of plants, animals, waste products, and fertilizers
- High levels can occur at the water source or from nutrient build up and breakdown in the water (over stocking, algae die-off, lack of water changes, fertilizer application nearby)
- Treatment: Water change to decrease, clean the tank/pond of extra plant or algae and debris that you can. if large scale you can place a phosphate binding filter or phosphate binding chemicals into the water.
Copper
- Aim for zero ppm, no more than 2.0 mg/L during copper baths
- Higher in soft water
- Cause- high levels from water source, treatment with bath, algae treatment
- Toxicity: osmoregulation dysfunction causing high levels of blood potassium from kidney failure/toxicity, immunosuppression, damage to lateral line organ, generalized multi-organ