Backyard ecosystem ponds should be easy to look after and understanding some of the basics will go a long way in making sure they thrive and evolve in all the right ways. This article takes a deep dive into understanding water chemistry basics so you can get your head around the importance of maintaining balance in your natural pond’s ecosystem.
The direct benefit in properly maintaining particular parameters within a pond ecosystem is a healthy pond, more diversity of life, better water clarity and general pond cleanliness.
The most important pond parameters we should aim to monitor are:
- pH
- GH (Total Water Hardness)
- KH (Carbonate Hardness)
- Nitrite
- Nitrate
- Chlorine
Use a reputable water test kit to test for these parameters, test kits for each of these are available for individual parameter testing or you can use an all in one test strip such as the Oase AquaActiv QuickSticks 6 in 1 Water Test strips.
pH in Pond Chemistry
pH measures how acidic or alkaline the water is, it is a scale of numbers from 0 to 14, with the number 7 being neutral.
Some fish and plants have specific pH requirements to thrive based on the water chemistry from their natural environment that they have evolved to live within.
If the required parameters are not met for the fish, they can have difficulty breeding and developing, may have difficulty breathing and in extreme cases, they can also be burnt by the water and die.
The best pH level for your pond will vary depending on the fish you are keeping.
Goldfish will prefer a slightly alkaline water with a pH of 7.5 but can be kept within the range of 6.5 to 8.0
Rainbowfish and other natives are best kept neutral around 7.0 but will also be happy between 6.5 and 7.2
GH or General Hardness in Pond Chemistry
General hardness is the measure of how 'hard' or 'soft' water is. It is measuring the level of dissolved minerals within the water. Water with lots of dissolved minerals is considered hard and water with little no no dissolved minerals is considered soft.
GH is important to fish and plants as they need the correct levels of minerals for healthy bodily functions such as muscle and bone development and plant growth. The little organisms such as dragonfly nymphs will also use these minerals for exoskeleton development.
For most ponds containing native fish or gold fish, a GH between 5-10 is recommended.
If the GH of you pond is too high the solution is not always the same, for example; if the GH is too high from an overdose of GH additive, simply perform a 20% water change and retest the GH after a few hours. (ensure the water you are refilling the pond with has a lower GH than the pond itself)
If your tap water is very hard, we would recommend using rainwater tanks to counter this problem as rainwater has a very low GH, it is much easier to add mineral than take it away.
KH or Carbonate Hardness
KH is probably one of the most important pond parameters, it is the measure of the level of carbonate and bi-carbonate ions within the water. These ions are important as they help to stabilise the waters pH and also ensure effective biofiltration, the basis of an ecosystem pond.
It is vital to monitor KH levels as they are consumed by biological processes within the pond. As fish breathe in the pond they are producing carbon dioxide which consumes KH. The breakdown of fish waste and plant material also demands KH to be consumed.
The KH level for most pond should test at 5 dKH but can be within the range of 4-8 dKH.
KH can be lowered by performing 10-20% water changed with rainwater or water with a lower KH level.
Nitrite
Nitrite is the second product along in the nitrogen cycle. Fish waste and decaying organic matter produces ammonia, the bacteria within your ecosystem will then convert this ammonia into nitrite and then nitrate. Although not as toxic to life as ammonia, nitrite can still be dangerous to fish as they breathe it in.
Nitrite levels are important to monitor in a pond as in the early stages of a pond you can measure to see how healthy the population of bacteria is and how it is progressing within the ecosystem. Long term monitoring of nitrite is also helpful as this will give you an indication as to the status of the bacteria colony, for example if it has crashed or is struggling within the ecosystem, or why your fish are lethargic or unhappy.
Ideally, your nitrite should always be 0.0 as an established pond will have sufficient populations of bacteria to eliminate the nitrite. If your nitrite is reading higher than 0.0 there could be a few issues to address such as overstocking of fish, insufficient filtration, overfeeding of fish or plants or lack of water circulation.
The most effective relief for the fish within the pond if there is a nitrite problem is to perform a 30% water change, however it is not a long term solution and your long term solution will depend on the problem the pond is experiencing.
Nitrate
Nitrate is the final product within the nitrogen cycle. It is the least toxic to fish, however is still toxic in high levels and with long term exposure. Nitrate is also a food source for plant life.
Nitrate is important to monitor as high level exposure is harmful to fish and it will also indicate when general maintenance or water changes need to be performed. Plants will absorb nitrate as a fertiliser and the more plants within a pond’s ecosystem, the healthier and cleaner the water will be for fish and other life.
Ensure nitrate is always below 60ppm (parts per million) but preferably as close to 0.0 as possible. Water changes are the best method for reducing nitrate and the addition of more plants are the best method to maintain a low nitrate level.
Chlorine
Chlorine is in our tap water to protect us from harmful micro-organisms and bacteria, however in a pond, chlorine will be harmful to most inhabitants such as the beneficial bacteria, aquatic insects and even fish.
Having undetectable levels of chlorine is necessary for the long term health of the pond and to ensure the ecosystem can develop without taking any backward steps.
Chlorine should always be 0.0 in a pond.
