Submersible pumps are simple and easy to install - all you do is place them in the water at the recommended depth. Basic pumps incorporate a fountain jet with an adjuster to control the height of the jet.

More versatile pumps have another outlet for a hose to supply a filter, waterfall or spout. Fit the outlet with a T-piece and you can supply two of these, or use two smaller pumps instead to supply each one separately.

These pumps are fitted with foam pre-filters to screen out particles that could damage the pump and block fountain jets. These pre-filters need frequent attention, but can be swopped for a Uflo version (by Rotorflush) that reduces the maintenance considerably. The pump in the photo has a Uflo pre-filter.

Other pumps include a filter and ultraviolet clarifier (UVC) unit.

Alternatively, choose a direct-drive (also called sump or solids-handling) submersible pump, which costs more than the other pumps, but can cope with particles up to 10mm (0.4 inch) depending on the model. These more powerful pumps are good for taking coarse material to an external filter, and for driving a waterfall. If you use one in a murky pond, fit a pre-filter to prevent the fine jets from blocking up.