Slate Sphere Water Feature Instructions
Installation & Care
Installing your slate sphere water feature
The whole job is straightforward: dig a hole, drop in the reservoir, sit the sphere on top and plug it in. No plumber, no electrician, no pond liner. These instructions cover every size from 400mm to 900mm.
Quick start
The short version. Every step is explained in full further down.
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Step 1
Pick the spot
Level, firm ground within 10m of an outdoor socket. Check for buried pipes and cables first.
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Step 2
Dig and set the reservoir
Bed it on 100mm of sharp sand, level it, and backfill so the rim finishes flush with the ground.
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Step 3
Fit pump and pipe
Sit the pump to one side of the reservoir floor and push the flexible pipe onto its outlet.
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Step 4
Fill with water
Fill until the pump is well under the surface. It must never be allowed to run dry.
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Step 5
Grid, then mesh
Drop the galvanised grid onto the rim, then lay the fine mesh over the top of it.
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Step 6
Sphere on, plug in
Feed the pipe through the mesh into the sphere, lower it into place, switch on and set the flow.
How it all fits together
A cut-through of a finished installation. Nothing is glued or plumbed — every part simply sits on the one below it, so the whole feature can be lifted apart again for servicing.
- 1 Handcrafted slate sphere
- 2 Water outlet at the crown
- 3 Flexible feed pipe
- 4 Decorative stone (your choice, bought separately)
- 5 Fine mesh — keeps leaves out and stone up
- 6 Heavy-duty galvanised grid
- 7 Pump, fully submerged, set to one side
- 8 Reservoir, rim flush with the ground
- 9 100mm sharp sand bed
- 10 Cable to outdoor socket, up to 10m
Before you start
A little preparation here saves a lot of work later on.
In the box
- Slate sphere, pre-drilled and pallet-fixed
- Reservoir
- Galvanised grid (plastic lid on the 400mm)
- Fine mesh
- 1200lph Pondtec pump with 10m cable
- Flexible feed pipe
You'll need to supply
- Spade and a barrow for the spoil
- Two bags of sharp sand
- Spirit level and tape measure
- Garden hose
- Scissors or a sharp knife for the mesh
- Decorative stone or cobbles to dress the top
Sizes and dig dimensions
| Sphere | Weight | Reservoir | Hole to dig |
|---|---|---|---|
| 400mm | 30kg | 67cm dia × 35cm deep | 77cm dia × 45cm deep |
| 500mm | 55kg | 85cm dia × 53cm deep | 95cm dia × 63cm deep |
| 700mm | 90kg | 112cm dia × 53cm deep | 122cm dia × 63cm deep |
| 900mm | 150kg | 112cm dia × 53cm deep | 122cm dia × 63cm deep |
Dig sizes allow 100mm of sharp sand underneath and roughly 50mm of backfill room all round.
Full instructions
Work through these in order. Steps 1 to 6 are the groundworks; 7 onwards is the assembly.
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Choose the position
Pick firm, reasonably level ground with an outdoor socket within 10 metres — that's the length of the pump cable, and it should not be cut, extended or joined.
- Keep it clear of overhanging trees where you can. Less leaf fall means less cleaning.
- Somewhere sheltered from strong wind loses less water to spray.
- Leave enough room to walk right round it with a barrow while you work.
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Move the sphere close to its final position
Do this while it's still on the pallet and before you dig. The spheres are heavy — 30kg at 400mm up to 150kg at 900mm — and moving one across a garden is far easier over flat lawn than around an open hole.
Lifting Use lifting straps and enough help to move it safely — check the weight in the table above. For a 900mm sphere, ask the delivery driver to place the pallet as close to the spot as they can get. Never roll a sphere over the finished grid or mesh. -
Mark out and dig
Set the reservoir on the ground and scribe round it with a spade, then step the mark out by about 50mm all round to give yourself backfill room. Dig to the depth in the table — reservoir depth plus 100mm for the sand bed.
Keep the sides of the hole reasonably square and the base flat. Barrow the spoil well clear; you'll need the space.
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Lay the sand bed
Spread 100mm of sharp sand across the base of the hole and rake it flat. A concrete foundation is not usually needed. The exception is a 900mm sphere going onto soft or waterlogged ground — on that, pour a concrete base and backfill the sides.
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Set the reservoir and level it
Lower the reservoir in and check it with a spirit level across the rim in two directions at right angles. Add or scrape away sand until it reads level both ways.
Why it matters If the reservoir is out of level, the sphere sits out of level too, and the water runs off one side instead of down all of them. You'll lose water outside the grid and be topping it up constantly. Get this right and everything after it is straightforward. -
Backfill around the sides
Work fine soil or sand into the gap around the reservoir a few inches at a time, firming as you go so there are no voids left to settle later. Finish so the rim of the reservoir is flush with the surrounding ground.
- On ground that slopes towards the feature, finish the rim 10–20mm proud instead. That stops soil washing in during heavy rain, and the decorative stone hides the difference.
- Re-check the level once you've finished backfilling.
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Fit the pump and the feed pipe
Sit the pump flat on the floor of the reservoir, towards one side rather than dead centre. Push the flexible pipe firmly onto the pump outlet, and run the cable up and out over the rim.
Worth doing Placing the pump off to one side means you can lift a section of grid later and reach it without moving the sphere. It costs you nothing now and saves lifting the sphere every time the pump needs a rinse. -
Fill the reservoir
Fill with clean tap water until the pump is well below the surface — near the top of the reservoir is right. There's nothing to prime and no chemicals to add.
Never Never switch the pump on before it is submerged. Running dry, even briefly, will damage it. -
Fit the grid, then the mesh
Lower the galvanised grid onto the reservoir rim so it beds down evenly. Then lay the fine mesh over the top of the grid, overlapping the edges by about 50mm all round, and trim it to shape.
The mesh does two jobs: it keeps leaves and debris out of the reservoir, and it stops your decorative stone dropping through the grid into the water.
Order matters Mesh goes on after the grid and before the sphere. If you sit the sphere down first you'll be lifting it again. -
Feed the pipe up and set the sphere
Snip a small cross in the mesh where the pipe needs to come through, roughly at the centre, and pull the pipe up through the grid and mesh. Leave plenty of slack.
With help, lift the sphere over the opening, push the pipe into the outlet in the underside of the sphere, and lower the sphere squarely onto the centre of the grid. Keep the pipe running straight up the core — a kink here is the most common cause of a weak flow.
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First run and flow adjustment
Plug into an outdoor, RCD-protected socket and switch on. Expect a few seconds of spluttering while air clears the pipe, then water should dome over the crown of the sphere and run evenly down every side.
- Too much and it throws spray past the grid — turn the flow adjuster on the pump down.
- Too little and it dribbles down one face — turn it up, and check the pipe isn't trapped.
- Aim for a thin, even sheet of water. That's what makes the slate look wet and dark.
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Dress it with stone
Spread your chosen cobbles, slate chippings or pebbles over the mesh to hide it, working right up to the base of the sphere. Leave the section of grid above the pump a little easier to lift.
Run it for an hour and watch where the water lands. If any is escaping past the stone, drop the flow slightly. That's the job finished.
Where to put the pump
Plan view, looking down into the reservoir before the grid goes on. The dotted circle is where the sphere will land.
Two rules for pump placement
Off to one side. Anywhere outside the dotted circle works. Once the sphere is on, that's the only part of the reservoir you can reach by lifting a grid section — and you'll want to, every month or two.
Flat on the floor, not against a wall. A pump vibrating against the side of the reservoir hums audibly through the whole feature. If you can hear it, slide a paving slab offcut or a rubber mat underneath.
Looking after the pump
The pump is the only moving part. Treat it well and it will run for years.
Every week in summer
Check the water level and top up with a hose. The reservoir is generously sized so this is a two-minute job, but evaporation is faster than people expect in hot, breezy weather.
Every one to two months
Unplug at the socket. Move the stone aside above the pump, lift the mesh and that section of grid, and lift the pump out.
- Open the filter cage and rinse the foam in clean water
- Clear any grit or leaf matter from the inlet
- Check the pipe hasn't worked loose from the outlet
- Refit, replace grid and mesh, then plug back in
Once a year
In a hard water area, twist the front cover off, lift out the impeller and soak it overnight in a weak vinegar solution to clear limescale. Rinse and refit.
If the water greens up
Full sun encourages algae. Empty the reservoir, wipe it out, refill with fresh water and refit the mesh properly — most greening starts with debris getting in past a badly seated mesh.
Through the winter
Slate is unaffected by frost. The feature stays exactly where it is.
Leave it running — the easy option
There's no need to bring anything indoors. Moving water is far slower to freeze than still water, so the simplest thing is to let the pump run continuously through cold spells.
- Keep the water topped up — a low reservoir freezes first
- Sweep autumn leaves off the mesh before they mat down
- Check the flow after a hard frost
Shutting down instead
If you'd rather turn it off for the winter, don't just switch it off at the socket and walk away.
- Unplug at the socket
- Lift the pump out and drain it
- Store it somewhere frost-free, in a bucket of water if you can — the seals last longer wet
- Leave the pipe in place and the reservoir covered
Troubleshooting
Almost everything below comes down to water level, a kinked pipe or a blocked inlet.
No water at all when I switch on
Switch off at the socket first. Check the water level — if the pump isn't fully submerged it won't pick up. Top up and try again.
If the level is fine, the pipe has most likely come off the pump outlet, usually knocked loose while the sphere was being lowered. Lift the grid section above the pump, push the pipe firmly back on and refit.
The flow is weak, or runs down one side only
Work through these in order:
Flow adjuster. Check it hasn't been knocked down to minimum.
Kinked pipe. The commonest cause. If the sphere was lowered with slack pipe trapped underneath, the pipe folds. Lift the sphere, straighten the pipe and trim any excess.
Blocked inlet. Unplug, lift the pump and rinse the filter cage.
Sphere out of level. If water only runs down one face, the grid or the reservoir beneath it isn't sitting level. This one needs the sphere off and the bedding corrected.
It's noisy, or humming
A rattle or hum almost always means the pump is touching the side or base of the reservoir and transmitting vibration. Unplug, lift the grid, and sit the pump on a rubber mat or a slab offcut, clear of the walls.
A gurgling or sucking noise means the water level has dropped too low. Switch off and top up straight away — don't let it keep running.
I'm topping the water up constantly
The reservoir is closed, so genuine leaks are rare. Losing water quickly usually means water is escaping past the edge of the grid rather than draining back into the reservoir.
Turn the flow down until the water sheets down the slate rather than jetting off it, and check the sphere is centred on the grid. In an exposed, windy spot, expect higher losses regardless — a lower flow setting helps.
The slate looks pale and grey, not black
That's dry slate. It lightens as soon as the water is off and darkens again within a minute of switching on. Natural slate also carries variation in tone and grain from piece to piece — every sphere is hand-built from individual slate pieces, so no two look the same.
Stone from the top has fallen into the reservoir
The fine mesh is what prevents this, so it has either been left out, not overlapped far enough, or torn where the pipe passes through.
Unplug, lift the pump and remove any stone that's gone through — loose stone drawn into the impeller will damage it. Then refit the mesh with a 50mm overlap all round and only a small cross cut for the pipe.
Stuck on something?
We'd rather talk it through than have you guess. Our water feature team is here seven days a week.