From the team at Byrkley Aquatics & Aquascaping, Burton on Trent — nearly 40 years of helping fishkeepers and water garden owners get it right.
When people say "water feature," we don't mean a pond. We mean a self-contained fountain, a reservoir hidden below ground or in a base, a pump pulling water up through a pipe, and a spillway, bowl, or urn where it tumbles back down. Think millstone fountains, tiered urns, obelisks. The same basic principle as the Trevi Fountain, just at garden scale.
That distinction matters, because a water feature behaves very differently to a pond. There are no fish, no plants, and no real ecosystem doing any of the work for you. Everything that keeps the water clear and the stonework free of slime and scale comes down to the pump, the reservoir, and how consistently you look after both.
Why Water Features Turn Green and Slimy So Fast
In a pond, plants and fish waste create a rough balance — algae has competition. In a water feature, there's nothing competing with it at all. Algae only needs sunlight, water, and a source of nutrients, and a water feature happily provides all three: leaves and garden debris blow in, dust and bird droppings settle on the bowl, and constant splashing keeps everything damp and ideal for growth.
That's why a water feature left untreated for a few weeks in summer can turn green or slimy noticeably faster than a garden pond of the same size. Without plants pulling nutrients out of the water, there's nothing slowing algae down except what you do yourself.
The Pump Is Doing All the Work
In a pond, the pump supports water quality. In a self-contained water feature, the pump is the water feature — no flow, no fountain.
Because reservoirs are usually small relative to the amount of splashing and spillage, debris collects and clogs the intake strainer far more quickly than in an open pond. A pump working against a partially blocked strainer runs hotter, moves less water, and wears out faster. It's worth checking and rinsing the intake regularly through the months your feature is running — weekly in autumn when leaves are falling, less often the rest of the year.
If the fountain's flow has visibly dropped, or the sound has changed, that's almost always a strainer or impeller partially clogged with debris, check that before assuming the pump itself has failed.
The Reservoir — Small Volume, Fast Problems
Because a water feature's reservoir is much smaller than a pond, everything happens faster in it, good and bad. There's less water to dilute a problem, which means algae, debris, and treatment doses all have a bigger relative effect than they would in a pond of the same footprint.
A mesh or grid cover over the reservoir opening keeps leaves and larger debris from falling straight in, which is by far the easiest way to cut down on maintenance. It's also worth doing a full clean of the reservoir at least once a season, removing the pump, sponging out sediment, and giving the bowl or spillway surfaces a scrub, rather than only ever topping up and treating.
Evaporation Is a Bigger Factor Than You'd Think
Water features lose water fast. The constant splashing and spraying dramatically increases the surface area exposed to air compared with a still pond, so evaporation rates are noticeably higher, especially in a warm summer or a feature that sits in direct sun.
This matters for two reasons. First, low water levels can cause a pump to run dry or suck air, which will damage it quickly, check the level regularly rather than waiting for the sound to change. Second, and just as important: whatever water treatment you're using needs reapplying every time you top up. Topping up dilutes whatever's already in the water, and because a water feature's reservoir is small, that dilution effect is bigger and faster than it would be in a pond. A lot of "why isn't this treatment working" conversations we have in the shop come down to someone treating the feature once, weeks ago, and topping it up regularly since without ever treating it again. Get into the habit of dosing after every top-up, not just when you first set it up.
Limescale and Staining — The Problem Ponds Don't Have
This is the one that catches people out, because it's not really an algae issue at all. Water features are almost always fed from the tap, and depending on how hard your water is, mineral deposits build up on spillway edges, bowls, and stonework as water evaporates and leaves the dissolved minerals behind. Over time this shows up as white, chalky staining or a rough scale that's separate from, and often alongside, any algae growth.
A general algae treatment won't touch limescale. If you're getting a white or grey crust rather than green slime, you need a descaler suitable for use with a running pump, not an algaecide. Worth checking which one you're dealing with before you buy anything, since treating the wrong problem gets you nowhere.
Algae Control Without Plants to Help
Since there's nothing biological competing with algae in a water feature, you're relying entirely on routine cleaning and the right product. A stiff brush and a scrub of the bowl and spillway surfaces every couple of weeks through the warmer months keeps algae from ever establishing a real foothold, it's far easier to stop a light green film becoming established than to remove a thick growth later. An algaecide or algae inhibitor added to the reservoir helps keep the water itself clear between cleans, but it works best as a supplement to regular scrubbing, not a replacement for it.
Positioning matters too, where you have any choice in it. A feature in full sun all day will need more frequent attention than one with some shade for part of the day.
Check Before You Treat: Pets and Wildlife
Water features are often more accessible to pets and wildlife than a pond, precisely because they're small, shallow, and usually sit right in the middle of a patio or border. Dogs and cats will drink from them, birds bathe in the bowl, and it's worth checking any product label for how it affects visiting animals before you dose the reservoir.
If you've got a dog that regularly drinks from the feature, or you know birds and other wildlife use it, it's worth prioritising pet and wildlife-safe formulations even if it means a slightly different product to the strongest algaecide on the shelf. If you're ever unsure what a treatment is safe around, ask us, it's a quick check and worth getting right.
Seasonal Maintenance — A Realistic Timeline
Spring is when to get the feature running again properly: give the reservoir a full clean before switching back on, check the pump and strainer after months of possible disuse, and scrub off any staining or algae that built up over winter.
Summer is about staying ahead of things: top up regularly and re-treat every time you do, keep an eye on evaporation in hot weather, and scrub the bowl and spillway before algae gets a proper hold.
Autumn is netting and clearing season. A mesh cover over the reservoir earns its keep here, falling leaves are one of the fastest ways to clog a strainer and foul the water if left to sit and rot.
Winter is different to a pond, and this is the one people get wrong most often. There are no fish to keep alive over winter, so the priority isn't keeping the feature running — it's protecting the pump and stonework from frost damage. In freezing weather, standing water left in pipework or a shallow bowl can freeze, expand, and crack stone, resin, or fibreglass features, and can damage a pump left in situ. Most water features are best drained down and the pump removed, cleaned, and stored somewhere frost-free for the winter, rather than left running or simply switched off in place.
Mistakes We See Most Often
Treating it like a mini pond. Without fish or plants, the balance is completely different — algae has no competition, so it needs more consistent manual intervention, not less.
Ignoring a clogged strainer. A drop in flow is almost always debris, not pump failure. Check there first.
Topping up without re-treating. Evaporation is high and the reservoir is small, so dilution happens fast. Re-dose every time you top up.
Treating algae when the problem is actually limescale. They look similar at a glance but need completely different products.
Leaving it running or full over a hard frost. Freezing water can crack the feature and damage the pump. Drain down and store the pump indoors for winter.
Only ever treating the water and never scrubbing the surfaces. Chemical treatment helps, but regular manual cleaning of the bowl and spillway is what actually stops algae and scale building up in the first place.
What to Do Next
Our Water Feature Care range is stocked with the treatments, descalers, and pump accessories mentioned in this guide. If you're not sure whether you're dealing with algae or limescale, or want advice on winterising your particular feature, bring a photo in or give us a call — we're happy to help you work out exactly what it needs.
Byrkley Aquatics & Aquascaping — inside Byrkley Garden Centre, Rangemore, Burton on Trent. Established 1987.