Looking after concrete pieces

Why it happens: water gets into a fine surface line, the temperature drops, the water expands, the line widens. Or the ground under the base has shifted and put pressure on the bowl. Most fixable cracks are under 2 mm wide.

The fix:

1. Drain the bowl. Clean and dry the cracked area with a brush.
2. Run a putty knife of concrete crack filler along the crack, pressing it in. Smooth flush with the surface.
3. Let it cure 24 hours before refilling with water.
4. While you're there, give the whole bowl a coat of clear pond sealer (see repair #4) — it'll stop the next one starting.

Find the leak first: drain the bowl, leave it to dry overnight, then fill it back up and watch the outside. Wherever a damp patch appears on the outside of the bowl is your leak point.

The fix:

1. Drain again and dry the leak area thoroughly — silicone won't bond to a damp surface.
2. For a single spot, apply pond-safe silicone with a caulking gun. Press it in, smooth with a wet finger.
3. For a hairline that runs across more of the bowl, brush on two coats of clear pond sealer instead — it forms a flexible membrane across the whole inside.
4. Either way, cure for 48 hours dry, then refill.

Important: never use bathroom or kitchen silicone. They contain biocides that kill fish, frogs and birds.

First, a note on pumps. Submersible pond pumps are a wear item — they're consumable, like a printer cartridge or a car battery. Budget pumps last 1–2 years. Premium pumps last 3–5+ years. Whichever you have, the moving parts wear out and the seals eventually leak. This isn't a fault, it's how pumps work.

Before you replace, check the obvious:

1. Cable plugged in, GPO has power.
2. Water level above the pump intake (most pumps die from running dry).
3. Hose not kinked or blocked.
4. Impeller not clogged with limescale or debris — see descale below.

Descale the impeller: unplug the pump, lift it out, leave overnight in a bucket of 1:4 white vinegar and water. Brush the impeller gently in the morning. Reinstall. About a third of "dead" pumps come back to life after this.

If it's still dead, replace: measure the height from the top tier down to the bowl ("head height"), add 10% for losses in the hose. That's the minimum lift the new pump needs.

Matching size to fountain:

• Tabletop or small bird bath (under 50 cm): 500–1000 L/h
• 2–3 tier fountain (1–1.5 m): 2000–3000 L/h
• 4-tier or large fountain (1.5 m+): 4000–5000 L/h

Warranty matters more than price. The pumps below come in two tiers. Whichever you buy, save the receipt and register it with the manufacturer when it arrives — if the pump dies inside the warranty period, the manufacturer replaces it, no questions asked.

The single biggest thing you can do to extend the life of a concrete piece. Sealing slows water absorption (so freeze-thaw can't crack it), keeps lime from leaching back out, and stops moss taking hold in shaded spots.

The how:

1. Drain and dry the piece. Give it a sunny week off — sealer doesn't bond to damp concrete.
2. Brush the whole surface clean with a soft brush. No detergents.
3. Apply two thin coats of water-based clear concrete sealer, 4 hours between coats. Inside and out of the bowls.
4. Cure 24 hours dry before refilling.

Done once every 2–3 years, this is the difference between a piece that lasts 10 years and one that lasts 30+. Quietly the most important thing on this page.