Changes in the weather and a ponds environment can cause many ponds to have water problems. These are particularly prone at opposite times of the year in summer and winter. As with most things in the garden, early detection and swift treatment are the best way forward; battling the causes of water problems is much easier than the causes. Leaving ponds with bad or problematic water can cause your wildlife and plants to die. Below is a short list of the most common causes of pond water problems and some of the solutions you can implement.
In chemistry, pH is the measure of how alkaline or acidic a solution is. It is the measure of the hydrogen ion activity within the solution. The pH runs from one (very acidic) through to 14 (very alkaline). Most ponds require a pH between 6.5 and 9 for wildlife and fish to flourish; anything over these extremes can quickly cause plant life and fish to suffer. The easiest way to measure your ponds pH is to take 5 cups of water from the pond. This allows you to get an average over the whole pond. You can then add this to a pH testing kit, which are available from most online pond stores such as Swell UK. Take two pH readings, one in the morning and one in the afternoon, and then average these out. Pond pH can fluctuate at different times of day. A higher pH can be the result of the presence of algae cause by your ammonia and nitrite levels. If the pH level is fluctuating then you can use pH buffer to help neutralise the problem. It is recommended to be very careful when changing the pH as a quick drop or rise in pH can be harmful to fish as they do not have the time to adjust.
Ammonia is produced as the bi-product of waste material in a pond. This is why it is nearly always recommended to not situate a pond beneath deciduous trees, as fallen leaves can land in the water. Ammonia can be produced from dead worms and dead algae in the pond and is also a waste product from any fish. High levels of ammonia in pond water are toxic to fish and other pond life. High levels of ammonia also increase the pH of the pond. Ammonia is part of the nitrogen cycle of all ponds so it is only very high and very low quantities that cause problems. Ammonia is turned into nitrite by ammonia oxidising bacteria in the water. Ammonia can be tested using a similar method to pH and kits can be bought from most pond stores. A sign of high ammonia levels is the development of an algae bloom. One of the best ways to relieve an ammonia problem is to use a pond vacuum to remove some of the dead material from the bottom.
Related to ammonia is the problem of nitrite levels. This is the following stage to ammonia breakdown in the nitrogen cycle. Whilst not as toxic as ammonia, high nitrite levels can also cause serious problems for your fish and pond life. Nitrite is converted to nitrate by nitrite oxidising bacteria which in turn is converted to nitrate by denitrifying bacteria. Nitrite and nitrate levels can be tested using a kit similar to ammonia testing kits, again available from most pond stores. Nitrate can be a particular problem if you are using artificial fertilisers and garden compost close to your pond as the run off can leach into the water. The classic symptom of high nitrate level is an algal bloom.
Algal blooms are the cause of high ammonia and nitrate levels. Whilst small levels of algae is advantageous for your pond as it helps to turn nitrate into nitrogen, once an algal bloom forms, covering your pond surface, it has become a problem. If a pond appears to have a green scum across its surface, then there is an algal problem. An algal problem causes a lot of dead plant matter to sit on the pond bottom which increases ammonia, nitrite and nitrate levels. All of these are particularly harmful to the fish and pond life. High levels of ammonia cause fish to become lethargic and constantly high levels cause fish to fall into a coma before dying. High levels of nitrite cause brown-blood disease which prevents fish from absorbing oxygen. A common symptom of high ammonia and nitrite levels is your fish gasping at the air above the pond surface. The easiest way to combat algal growth is to use an algae buster and then follow the previous recommendations for high ammonia and nitrite levels.
The final most common pond water is water hardness. Water hardness refers to the amount of mineral, primarily calcium and magnesium, in your pond. Too many minerals can cause algal growth but too few minerals can prevent any vegetation from growing at all. A good filtration system can help combat algae growth and testing your water hardness is relatively easy using one of the many kits available.
If your fish and vegetation seem to be suffering for any reason it is worth checking the water quality of your pond. However these are not the only causes as disease and pond aeration can also be problems. In addition maintaining healthy water quality in your pond can reduce the number of problems you get from disease. With any of these problems regular water changes and monitoring can help prevent them before they become a major problem.