How to Shade a Garden Pond from Excess Sunlight (Top Summer Tips)
Summer is a great time to watch a garden pond come to life; with plants blooming, fish becoming more active, and sunlight illuminating the water.
Even though most of us love the sun, too much sunlight can be a bad thing, and that also applies to garden ponds. Water exposed to the UV light of the sun without any period of shade can have all sorts of problems, ranging from algae bloom, decreased oxygen content, and really unhappy fish! These problems are more common for pond owners living in much warmer climates, or for smaller ponds which are more shallow and absorb heat faster. Both koi and goldfish also prefer a pond within a specific temperature range, and water which becomes too hot can cause a lot of unnecessary stress.
If your pond has a few hours shade a day, or is at least partially shaded throughout the day, you should not see any issues unless you live in a particularly hot climate. If you have a small pond with fish, or a heavy fish stocked pond, it may be a good idea to consider shading the pond for a certain amount of time each day to make fish more comfortable. It’s also a good idea to shade pond water if you’re having algae issues due to intensive sunlight, or you notice a lot of water is evaporating daily due to the heat. Providing shade will slow algae growth and make it more controllable, and will also slow the evaporation rate of water, which means less topping up with mains supply.
Even if you don’t get a huge amount of sun, providing extra shade can have benefits to both you and your fish, reducing overall pond maintenance and making fish just a little happier!
Benefits of Shading a Pond
1) Slows Algae Growth
Algae grow the fastest during the hottest months when sunlight is the most intense, and if left unchecked, they can quickly take over a garden pond. Ponds in the shade may still have issues with algae, as they can grow with minimal light, but providing shade will help slow down growth making it more manageable. A partially shaded pond will have much slower algae growth in comparison to a pond constantly exposed to sunlight. Too much algae can become a huge problem for a pond, especially one with koi or goldfish. As algae die off and more start to grow, massive amounts of oxygen are removed from the water by decomposing beneficial bacteria. During periods of algae blooms this process can reduce oxygen content in the water to dangerously low levels, putting huge stress on fish.
Shade will certainly help slow algae from growing, but if you’re already experiencing a rapid bloom, a more direct approach may be needed to get things under control first. If you already have major algae problems, check here for our full guide on algae control and how to remove it.
2) Improves Oxygen Levels
High temperatures reduce the oxygen holding capacity of water, meaning ponds will be holding less oxygen during the warmest summer months. Fish also become more active during summer, eating more as their metabolic rates increase. This increase in activity means the fish produce more waste, and beneficial bacteria will need to work harder to break down the excess. These bacteria require oxygen to function, just like fish, and may struggle to carry out their job as oxygen content decreases.
Shading a pond from sunlight will help lower the overall temperature and improve the capacity at which water holds oxygen. Algae also grow the fastest during the day, so slowing their growth by blocking sunlight will help improve oxygen for both fish and beneficial bacteria.
3) Makes Fish More Comfortable!
Both goldfish and koi prefer a pond within a specific temperature range, generally between 65 and 75 F degrees. They can certainly survive in much colder or hotter water, but that doesn’t mean it’s ideal for them. Warmer water temperature, along with pH, also has a direct effect on the toxicity of ammonia. This waste substance is very dangerous to fish, but the majority is safely removed by the beneficial bacteria living in your pond and filter box. Problems may occur during summer where fish produce more waste (ammonia) and temperatures are also high, which causes the ammonia to become more potent. Shade is just one thing that can help with this issue by allowing water more time to cool down from the sun, and giving bacteria more time to breakdown substances before they can build.
In much smaller ponds, such as preformed ponds, fish can literally boil to death if the water is exposed to constant sunlight throughout the day. Smaller ponds act as insulators, taking in heat and retaining it much more readily than a larger body of water. Even with aeration, shallow water may not be able to cool down fast enough, so providing shade is essential if you want to keep your fish healthy and happy in a small environment.
Methods to Provide Pond Shade
Option 1: Pond Plants (Real or artificial)
Shade Amount: Partial Shade
A great natural way to provide shade to pond water is to add pond plants! Both real or artificial plants will be able to provide shade, but only real pond plants will be able to give your water more oxygenation and help with natural filtration. The best plants for shading water and providing shelter to fish would be water lilies or lotus, as their foliage grows across the water, blocking a large chunk of UV light. Most floating plants would be ideal for adding shade to a pond, and luckily these come in both real and artificial varieties. If you just want some shade and shelter for your fish during summer, artificial floating plants will provide those benefits without requiring any hands-on maintenance. If you decide to go with real floating plants, it may take some time for them to grow and become established, but the results are fantastic in the long run!
As well as floating plants, marginal plants can also provide partial shade to a pond, creating areas where the water is cooler and less UV light penetrates. These kind of plants are usually added to the sides of a pond, fleshing out the embankments. A few can grow very tall with lush green foliage, and these provide the best shade to pond water. It’s less common for these kind of plants to have an artificial alternative, so if you don’t want to care for real plants, we recommend sticking with artificial floating types for best results.
On top of shading a pond and helping cool down the water, both types of pond plants also create “safe spaces” for your fish to hide when stressed or threatened. Plants provide a natural form of shelter which fish love to hang out around when they need to relax for a few hours away from the sun and everything else.
For more information on the best real pond plants and some good beginner choices, check our full pond plant article here.
Option 2: Shade Sails
Shade Amount: Partial-Full Shade
Unlike pond plants which only provide partial shade to the water, shade sails can provide up to full pond shade, and can be altered to suit your needs. These covers are generally made from durable UV resistant fabric, often polyproplyene, and work to block a large amount of UV light from penetrating into pond water. They’re fixed above ground and can be positioned to provide full shade or partial shade to a specific area of water, with most models blocking up to 90% of all UV light.
If you have particularly hot summers and a small fish pond, investing in a high quality shade sail is probably the single best method of cooling and shading your water. There is no maintenance required when installed, and due to the amount of UV light the material can block, it can reduce water temperature by a large amount daily. They will also work fine in larger ponds, allowing you to section off a shaded area of pond water for your fish to hide, and giving water a chance to cool as it circulates. They will also help reduce algae growth and deter airborne predators, such as herons, from taking pond fish.
A downside is they’re very noticeable and not something you can easily hide. Shade sails will also block sunlight from reaching regular pond plants, so you would need to make sure your plants can grow in partial shade or position the material so the sunlight still hits the plants. Other than this, however, shade sails are probably the best method of shading AND cooling pond water during summer, and we’d recommend them to anyone who has a fish in a full sun exposed pond.
Option 3: Pond Water Dyes
Shade Amount: Partial Shade
Another interesting method for shading pond water and blocking UV light is by using non-toxic water dyes! These kind of dyes are a popular method of algae control for larger bodies of water, such as lakes, where it’s not possible to install shaded covers or enough plants. In recent times they have also started to become popular for garden ponds, providing an alternative method to help reduce algae growth and block UV light from penetrating pond water.
The best pond dyes are made from non-toxic food-grade ingredients, which are the same dyes used to color food we consume on a daily basis. They come in a range of colors, with blue, turquoise, and black being the most popular and functional for blocking sunlight.
Blue dyes are a good all-round colour which will provide a more natural pond aesthetic and help block a large chunk of sunlight reaching through your water. They look great for most types of ponds, and we would recommend blue as a good starting choice for first time dye users. If you want maximum algae control and UV reduction, black dyes provide a much higher reflective surface and a darker water color. This color will absorb more UV light and reflect more light off the pond water as the dye becomes established, but the color is less natural in comparison to blue.
Pond dyes are safe for both fish and wildlife, and usually provide around 2-3 months of color before needing a top up. They will also help hide your fish from predators, as the dyes will make it much harder for flying animals, such as herons, to see your fish while overhead. Pond dyes won’t provide as much direct shade as plants or shade sails, but can be used alongside these options to help further control algae and reduce water temperature from UV light exposure.
Option 4: Fish Shelters
Shade Amount: Partial-full Shade…for fish!
Although they may not provide your entire pond shade, fish shelters are a great solution for fish needing to cool down during the hottest times of the day! These shelters are usually made from non-toxic plastic or mesh material, and are designed to sit on the bottom of your pond floor at the deepest point. They make great safe havens from predators, and give your fish a place to de-stress when needed. As well as this, both mesh and plastic designs will help to block UV light from penetrating a small area of the pond floor, providing fish a slightly cooler place to escape to.
Although they may not be suitable for small ponds with shallow water, they work great for ponds with at least 3ft+ of water depth. If you have pond plants which require plenty of sunlight and you don’t like the idea of a shade sail, a shelter should provide your fish enough UV protection to cool down when needed. If you have lots of fish, or larger koi, you can add multiple shelters in different areas of the pond for more places to hide in summer. As well as providing shade, they work great to stop herons taking fish, so would be a good addition to any koi or goldfish pond.
The choice of design is mostly down to personal preference, with both plastic and mesh working well to shade a fish pond. If we had to choose, we’d probably select a mesh shelter as they are softer (less chance of injury), easier to sink, and still provide good UV coverage.
For more information about shelters and some of the best models, check our full article here.