Pond Problem Solving - Water Quality

Alkalinity, or Carbonate Hardness (KH)

Alkalinity is the ability of water to resist changes in pH. Alkalinity is also known as Carbonate Hardness or KH. An alkalinity value of 100 to 300 ppm is good. These levels provide greater buffering and more stable pH.

Combining a low total alkalinity with submerged plants or algae can cause a day time alkaline pH and a night time acid pH. This is because plants produce oxygen during the day but not during the night. This 'pH shift' is stressful to your fish and can lower their resistance to disease if the situation continues. An excellent reference article is 'pH crash (no one is immune)'.

To increase alkalinity, add sodium bicarbonate or change the water.

Ammonia

Almost all of the ammonia present in your pond's water is from fish waste, primarily respiration, and it is toxic to your fish.

The amount of toxicity depends on how alkaline the water is. As pH increases above 7, the amount of ammonium transformed into ammonia increases dramatically. Water test kits measure the combined total of ammonia and ammonium, which should always read 0.0 PPM.

To reduce the toxic ammonia content, make a partial water change, decrease the amount of food you feed your fish, reduce your pond's fish load, add more filtration, or add a commercially prepared ammonia remover.

Chlorine & Chloramine

These chemicals are often added by water companies to make water more potable for human consumption. If you use municipal water treated by these chemicals, we recommend that the residual should not be more than .003 PPM when mixed in your pond.

Municipal water will lose much of its' chlorine by exposure to sun light in a time period of a few days, but that is not the case for chlorimines, which are much harder to break down. Chloramine can be neutralized by using chlorine & heavy metal neutalizer.

This is an excellent  reference article on treating your water for chloramine.

Heavy Metals

The solubility and toxicity of zinc, lead, aluminum and copper have a direct relationship to increases of pH and water hardness.

To remove heavy metals, use activated carbon filtration or chlorine & heavy metal neutalizer.

Nitrites / Nitrous Acid

Nitrite is the by-product of nitrosomonas bacteria breaking down ammonia in alkaline water.
Nitrous acid is the by-product of nitrosomonas bacteria breaking down ammonia in acid water.

These reactions are the first steps in the nitrogen cycle. As pH decreases below pH 7, the amount of nitrous acid increases dramatically and becomes more toxic. A test for these molecules should read 0.0 PPM.

To reduce toxic nitrous acid, make partial water changes, reduce the fish load, reduce the amount of food you're feeding your fish or adjust the pH.

Nitrates / Nitric Acid

Nitrates and nitric acid are the by-products of nitrobacter bacteria breaking down nitrites or nitrous acid. This is the second step in the nitrogen cycle. Unless found in large quantities, both are considered non toxic.

To control the amount of nitrates and nitric acid, make water partial changes or add plants.

Oxygen

Oxygen is needed for the normal day to day functions of a fish, and by the bacteria necessary for the breakdown of fish waste products in the nitrification process. The amount of oxygen consumed by the nitrification process takes away from the oxygen levels needed to keep your fish healthy and happy.

Water temperature has an inverse relationship to the amount of oxygen contained in that water - the higher the water temperature, the lower the oxygen saturation level. Other factors affecting the amount of oxygen in the water are fish load, organic load, medications, and the water turn over rate. Minimum levels of oxygen should be 5 PPM.

To increase the oxygen content, reduce the organic load by ridding the pond of any organic matter that is sitting on the bottom, increase the water turnover rate, add plants, reduce the fish load or add an aerator.

pH

The pH level of your pond is your single most important water quality measurement, as it affects the toxicity of your pond water. All values above pH 7 are termed alkaline and all values below pH 7 are termed acid.

Your fish can live in a wide range of pH, but the level should remain stable - and a reading of 7.2 to 7.8 is ideal. Use your water test kit to measure your pH levels in the morning and evening to keep an eye on "pH shift", and do not adjust your pH until your alkalinity is stable and pH shift is minimized. An excellent reference article is 'pH crash (no one is immune)'.

To adjust your pH levels perform partial water changes or use pH Up or pH down.