Hilton & Green Landscaping builds and looks after garden ponds in Norwich and the surrounding villages. Summer is when ponds look their best and cause the most head-scratching, so good pond maintenance summer routines matter. Warm water, longer days and more sunlight all push algae along, and a pond that was crystal clear in April can turn pea-green by the end of June.
Here's how we keep ponds clear through the warmer months, and what you can do yourself between visits.
Why ponds go green in summer
Green water is caused by single-celled algae floating in the water. They need three things: sunlight, warmth and nutrients. Summer hands them all three.
The nutrients usually come from somewhere you can control. Fallen leaves and silt on the bottom, fish food that nobody ate, fish waste, or lawn fertiliser washing in off the bank. Cut the nutrients down and the algae have less to work with.
Blanketweed is a different problem. That's the stringy green stuff that wraps round plant stems and pump housings. It thrives in the same conditions, and it tends to show up in ponds with plenty of light and hard water, which covers most of Norfolk.
A simple summer pond routine
Check the water level weekly
Ponds lose a surprising amount to evaporation in hot weather. A shallow pond can drop several centimetres in a week. Low water means a hotter pond, less oxygen and a pump that may run dry.
Top up with rainwater from a water butt where you can. Tap water contains chlorine and nutrients that can trigger an algae bloom. If you have to use the tap, add small amounts over a few days rather than a big refill in one go.
Keep the pump and filter clean
A blocked filter stops doing its job long before it stops making noise. Rinse filter foams in a bucket of pond water, not under the tap, so you don't kill off the helpful bacteria living in them. Check the pump intake for blanketweed and leaves every couple of weeks.
If you run a UV clarifier, remember the bulb loses strength after roughly a season of use even if it still glows. Replacing it at the start of summer is often the single easiest fix for green water.
Skim and scoop
Pull out blanketweed by hand or by twisting it round a cane. Leave what you pull out on the side of the pond for a few hours so any snails, insects and small creatures can crawl back in, then compost it.
Skim off floating debris before it sinks and rots. Anything that ends up on the bottom becomes food for next year's algae.
Don't overfeed fish
Fish eat more in warm weather, but it's easy to tip in more than they need. Feed small amounts and watch. If food is still floating after a few minutes, you've given too much.
Shade and planting do the heavy lifting
The most reliable way to keep a pond clear is to cover part of the surface with plants. Aim for something like half to two-thirds of the surface covered by mid-summer with water lilies, water soldiers or floating plants. Shade cools the water and takes light away from algae.
Submerged oxygenating plants such as hornwort compete with algae for the same nutrients and add oxygen at the same time. Marginal planting round the edge does the same job and softens the pond edge visually. We often combine pond work with planting and borders so the water feature sits properly in the rest of the garden rather than looking bolted on.
If a nearby tree is dropping debris into the water, or casting so much shade that nothing grows, a sensible reduction can help. Our tree surgery and pruning work often ties in with pond problems for exactly that reason.
Oxygen in hot weather
Warm water holds less oxygen than cold water. On a still, muggy night, fish can struggle, and you may see them gasping at the surface early in the morning.
Moving water helps. A fountain, a small waterfall or an air pump will all raise oxygen levels. If you already have a pump, running it through the night in a heatwave is worth doing. Removing a thick mat of blanketweed also helps, because when it dies off in bulk it uses up oxygen as it breaks down.
When to get help
Some problems don't respond to weekly tidying. Persistent green water despite a working filter, a leak that keeps dropping the level, a liner that has failed at the fold, or years of silt on the bottom all need hands-on work.
We handle pond builds, repairs, cleaning and replanting as part of our garden ponds service. That can mean a full clean-out with fish held in holding tanks, relining a section, upgrading a pump and filter to suit the actual volume of water, or reshaping the edges so the planting shelves work properly.
If the pond is part of a wider garden that needs regular attention, it usually makes sense to fold it into a garden maintenance visit so it doesn't get forgotten in August. You can see the areas we work in on our areas we cover page.
If your pond has gone green, sprung a leak, or you'd like one built properly from the start, call Hilton & Green Landscaping on 07711916180 and we'll come and take a look.