For our dedicated water gardeners, there is very little considered more disappointing that green water problems in your beautifully kept pond. Even more of a headache is the uncertainty of what is causing it and what is helping it! In this blog we will talk you through some of the causes and remedies for green water in your pond, together with an explanation of what it actually is! By the end of the blog, you will have enough know-how to advise all of your family and friends suffering with the same problem - how to tackle it once and for all!


One of the best things you will learn after reading this blog, is that tackling green water problems in your pond is not all that difficult and that there are a number of easy ways to reduce its effects!


Green water in ponds is caused when single celled algae reproduce. This mono cellular algae lives suspended in the pond water and is fueled by a lethal combination of sunlight and nutrients found within the water. Not exactly what you want to hear, right?! Both sunlight and nutrients are important for lots of different processes, habitats and creatures within your pond so these two factors cannot be reduced or controlled without sacrificing the benefit they bring to other elements of pond life. If you have a pond that is prone to green water, you will notice it beginning to emerge as the water starts to heat up during the sunnier days of Spring. Bummer!!


So who are the main culprits? That would be “Nitrates” (formed naturally from fish faeces, dead plant matter and old fish food breaking down), “Phosphates” and “Sunlight”. So here is the first clue in how to control some causes of green water problems in your pond. A) Clean out decaying plant matter such as dead decomposing leaves and plant parts. B) Cut and discard of your dead plant foliage by pruning your pond plants when they need it. C) Avoid over-feeding your fish so that you don’t have the excess food waste sitting on the surface of your pond for days.  Sunlight of course is difficult to avoid especially in an outside area!  Therefore a UV Clarifier is the only guaranteed way to clear green water, more about this later.  If you do not want a UV Clarifier then producing some sort of shade over the Pond or when installing the pond, siting this in a shaded area is also beneficial.  However to really enjoy the pond in full sun we always recommend a UV Clarifier.


So let’s take a look at chemical treatments and the natural control methods in how to reduce green water in ponds.


Chemical treatments such as our range of green water additives are very effective and fast acting, although it is always recommended that this form of control is applied with some long-term natural control methods to your pond, to prevent green water returning after the chemical treatment has been administered. One of the main things to consider when using chemical treatments for green water in ponds is to read the label carefully, checking that it can be used in conjunction with the fish or other amphibians that are living in and around the environment. One effective manmade remedy for green water problems is that of UV clarifiers, if not only for the fact that they have no effect on water quality then for the fact that they pose no threat on fish or plants. UV units are cheap to run and easy to install making them a great choice for green water control. Once combined with appropriate planting and a biological filter system, it can effectively help to keep your pond crystal clear. Pond skimmers are another great manmade gadget which help to reduce levels of green water in your pond by collecting all of the dead weeds and debris from the surface of the water before they sink to the bottom of the pond.


Some sensible planting together with avoiding over stocking of your pond with fish are two natural ways to reduce green water in your pond, but there are a number of other remedies to consider also. Because plants compete so much with algae for sunlight, it makes sense to introduce enough pond plants to take up around two thirds of the space inside it. Trees and dense shrubbery around the outside also act as good shade to prevent excessive sunlight exposure into the pond. Barley Straw has also been known to have great impact on green water in ponds. This may be a good choice for those who find that green water is still returning even with the above measure carried out.  The enzymes present inside barley straw are said to inhibit the growth of green water as well as blanket weed. Taking a few weeks before a difference is noticed, barley straw is available in pouches of the straw itself or as an extract. It may also be worth knowing that clearing the debris from the bottom of your pond once during the Spring and once again in the Autumn once the leaves have finished falling, should also go some way to reducing levels of green water.


So by following a few of these steps in reducing green water problems in your garden pond– or all of them, you should be well on your way to creating a biologically balanced ecosystem! If you found this blog useful – please give us the thumbs up! And don’t forget to share it with your fellow water gardener friends!