If a pond filter does not do what is expected of it, good advice is needed. The green water is still green, and it just can’t stay that way in a pond over the long term. But what is the reason that the filter couldn’t do anything? Or is that not his fault at all? How can the water be clarified at all?
Table of Contents
What makes the pond water green?
A green colored pond water is extremely “alive”. Countless floating algae cavort in it, which are microscopically very small. They cannot be seen individually with the naked eye, nor can they be effectively filtered. What is clearly noticeable is their green color, which can be so intense that the depth of view is limited to a few centimeters. One speaks of the so-called algae bloom because the algae find ideal living conditions and multiply explosively.
What are the causes of the enormous algae growth?
Excessive algae growth can only be observed in ponds where there is no ecological balance. Green water is more common in new ponds because the ecosystem has not yet developed and consolidated properly. A large change of pond water can also upset the ecological balance in the pond. The following factors also promote algae growth:
- strong solar radiation and thus water heating
- an excess of nutrients from overfertilization
- excess fish feed
- Lack of oxygen
React quickly is the order of the day
As soon as you notice that the pond water is turning green, you should react immediately. Floating algae multiply so quickly that their growth should be slowed down as quickly as possible. Removing them from the pond afterwards is more laborious and therefore takes time.
How can the green water be clarified?
Green pond water poses two challenges at the same time. First of all, the pond water should become clear again, and secondly, it should also remain clear afterwards. This requires knowledge of the causes and a bundle of measures that complement each other in a meaningful way, and of course a little patience. The measures are intended to achieve the following:
- Remove existing floating algae from the pond water
- curb further algae growth through short-term measures
- stabilize the ecological balance in the long term
Is water replacement a solution?
Even if the idea of a complete water exchange appears to be an obvious solution to green pond water, it would have the complete opposite effect. With fresh water, the pond is supplied with new nutrients, which in turn lead to new algae growth. The pond water would turn green again within a very short time.
Immediate measures for clear pond water
An immediate measure is to gradually filter the algae out of the pond water. The sooner you start, the sooner the green will fade and eventually disappear entirely. Since the algae are so tiny, the pond filter alone cannot do anything against them.
To filter out the floating algae, three components are required that work together to counteract the green color. These are:
- a filter
- a pond pump
- and a UVC clarifier, also called a pond clarifier
The filter process in detail
The pond pump conveys the green colored pond water to the UVC clarifier, which is installed in front of the filter. The UV light ensures that the floating algae clump together and thus gain volume. So connected to each other, they can now be easily filtered out.
If you reinstall a filter in your pond, a little patience is required until the result is visible. If there has been no change even after a month, it could be that the pond filter is too small for the pond.
Despite a powerful filter, the water can occasionally remain green. The algae growth is apparently unchecked that it easily replaces the filtered amount of algae. That is why it is important not to stop at filtering, but to counteract the causes of algae growth with other measures at the same time.
Use algae control agents
Algae control agents are commercially available that promise a decrease in the algae population. To do this, they intervene in their metabolism and thus make photosynthesis more difficult. Such a remedy takes 2 to 3 weeks to develop its full effect. When used properly, the agent should be well tolerated by desirable pond inhabitants such as fish, aquatic plants and beneficial microorganisms.
Check water quality
So that the filter does not work in vain against the green of the water, new algae growth must be stopped or at least reduced first. Since poor water quality is one of the most common causes of such pond problems, the current state should be clear. Water analysis sets are available in stores that measure the decisive values. It is ideal if the results of the measurements are within the optimal range:
- pH is between 7 and 8
- KH value from 5 to 12
- GH value from 8 to 12
- Nitrite value is below 0.15 mg / l
- Nitrate value is below 0.50 mg / l
If individual measurements deviate from the ideal value, you can counteract this with the help of commercially available water conditioners.
Eliminate excess phosphate
Phosphates are the basis of algae growth, which is why the phosphate content in pond water should be reduced.
First you have to check whether there are too many fish in the pond. 3 kg of fish per 1000 liters of water is an ideal figure. If the fish stock is above this value, you should part with some of the fish.
If possible, use low-phosphate food and only feed small amounts once a day. The amount should be small enough that the fish can eat it within 5 minutes. Generosity is out of place here, because more food really doesn’t have to be.
Special phosphate binders are also available on the market, some of which can even be integrated into the filter.
Pond plants as nutrient consumers
Optimal plant care of the existing pond planting is important for the biological balance of the pond. But not only the care also the selection of the plants plays an important role in the prevention of uncontrolled algae growth. Fast-growing plants consume a lot of nutrients and are therefore a natural food competitor for the unwanted algae. They are therefore also known as biological filters. The following three plants, among others, have proven themselves:
- Cornea
- Thousand-leaf
- Waterweed
However, due to their strong growth, these three pond plants also need more plant care. Occasionally thin them out to keep them from growing excessively.
Check or install capillary barrier
A capillary barrier separates the pond ecosystem from the rest of the garden. Among other things, it also prevents the exchange of nutrients. Without such a barrier, rainwater can easily flush nutrients from the surrounding garden soil into the pond. Capillary barriers that have already been installed should now be checked to ensure that they are fully functional.
A missing capillary barrier can also be retrofitted. The edge of the pond should be slightly elevated and ideally protected by a drainage ditch. This should go around the pond, about 15 cm wide and 15 to 30 cm deep. It is filled with coarse gravel. The rainwater can seep into this before it reaches the pond.
Optimize pond maintenance
Proper plant care also helps to prevent excess nutrients. Correct plant care includes, for example, promptly removing dead plant residues from the pond water. Even fallen leaves from nearby trees will soon have to be fished out of the pond water.
If biomaterial remains in the pond, it consumes the oxygen dissolved in the water during the rotting process. However, a lack of oxygen is one of the causes of algae growth. When rotting, organic material is also broken down into nutrients, which further fuels algae growth.
If plant care is neglected, perhaps due to lack of time, rotting material can lead to rotten sponge. This does not color the water green, but makes it cloudy.
Fertilizing is also part of plant care and is therefore on the pond owner’s to-do list. However, if the pond water is green, fertilizing should take a break. If you pay attention to your pond plants, you will notice in good time when they need a new fertilizer.
Increase oxygen levels
A high percentage of oxygen in the pond water is a good prevention against algae. So-called oxygen plants, such as green pennywort, naturally increase the oxygen content in the pond water.
In small ponds, a fountain also brings some oxygen into the pond water. Also consider buying a larger filter.
Keep away from direct sunlight
The catalog of measures to prevent algae bloom should also deal with solar radiation. Depending on the location of the pond, the water can receive excessive amounts of direct solar radiation in spring and summer. However, six hours a day should not be exceeded. If the pond gets more sun than it can handle, more shade is urgently needed. Since the sun cannot be prevented from shining, the pond owner must adequately shield his pond from it.
- Plant shrubs and small trees near the shore
- Bamboo grows quickly and keeps the sun out
- Floating plants on the surface of the water are helpful
If you have the option of attaching an awning, consider doing so, at least temporarily. Small ponds that are struggling with green water can also be briefly shaded with a large parasol. However, since a parasol is not suitable for continuous use, another solution must be approached in parallel.
Conclusion
The garden can be green, but not the pond water. If it turns green anyway, its ecological balance has long been disturbed. Fortunately, this can also be restored. While a filter filters out the floating algae, a number of measures help to improve the water quality and thus prevent new algae growth.
