What are KH Levels?
KH is the measure of carbonate hardness in your pond. Carbonate hardness is the amount of calcium carbonate in your pond. Calcium carbonates are very important. They feed the nitrifying bacteria that remove harmful ammonia and nitrates from your pond water. These bacteria are part of your ponds bio-filter. Without this, your pond would be under great threat and would rely heavily on your mechanical filtration system. KH levels should be around 125ppm but they can fluctuate safely by about 20ppm either way.
Unfortunately, as with low pH levels and low oxygen levels, the effects of low KH levels can’t be seen by eye. You may notice that your ponds condition will deteriorate, Ammonia and Nitrate levels will rise and your pond will become more susceptible to pH swings which will ultimately lead to a pH crash!
Ammonia, Nitrites and Nitrates
Ammonia is released into your pond when your fish excrete waste. The nitrifying bacteria that are fed by calcium carbonate then break down the ammonia and turn it into Nitrite. Nitrite is then broken down further, to its final state, Nitrate. Nitrate is the final by-product of Ammonia. All three of these can be dangerous to your fish and should be monitored carefully. Ideally, you should be removing any Ammonia in your pond to avoid it damaging your fish or breaking down further. Ammonia can cause Ammonia poisoning that can lead to death. Nitrites and Nitrates are not as dangerous. However, if your fish already have Ammonia poisoning they will be weak and susceptible to the irreversible effects of Nitrates.
Ammonia levels should be kept as low as possible. Ideally at 0ppm but they can be okay at 0.5ppm if your pH level is neutral. Remember, the higher your pH, the more toxic Ammonia becomes so it is best practice to keep the level low. Likewise, Nitrites should be kept as low as possible around 0.25ppm but ideally at zero. Finally, Nitrate levels should be around 20-60ppm.
Phosphate can be presented into pond water by many forms. One of them may be soil in planting containers before aquatic plants are planted into the pond, as there are fertilisers in the soil prior to planting to help them grow. Another reason may be tap water that is used to fill up the pond. Phosphate levels are generally quite high in tap water these days to help stop water pipes from corroding. The other major source is fish food. Fish food contain phosphates, as it is an essential part of a fish’s diet. Large amounts of the phosphate will pass straight through fish and be released as fish waste.
High Phosphate levels are a major cause of green water and blanket weed in a pond. If phosphate levels are kept low then algae growth will be limited within a pond.