Submersible Garden Pond Pumps - setting one up in your garden pond
The most commonly used pumps for pondkeeping are submersible -ie, they are designed to be positioned underwater. There are also dry-mounted pumps which can pull water out of a pond whilst remaining above the surface. Dry pumps are useful in certain situations such as gravity-fed filters often used in densley stocked koi ponds. They can be easier to maintain as they can be easily accessed and don't have to be fished out of the water. But by far the most common method is to locate the pump under the water so we will take a closer look at this. (Many submersible pumps can also be run 'dry' so this is worth checking before you buy). Submersible pumps have a hermitically sealed motor which prevents water ingress. Modern pumps are housed inside a strainer cage which prevents large particles entering the chamber and blocking the impellor. Older pumps utilised foam inside the strainer cage but this was prone to getting blocked over time so is rarely found with newer pumps. The pump should be positioned at the bottom of the pond yet within easy reach for maintenance. A top tip is to attach cord or rope to the pump so it can be easily lifted out of the pond - never lift a pump by its electrical cable as this is dangerous. Ideally maximum circulation should be created involving as much of the pond water as possible. For instance, if the pond has a waterfall then the pump should be located towards the opposite end of this otherwise if the pump was placed under the return flow of the water then only part of the pond water would be in constant circulation. If there is a lot of sludge in the pond then it may be necessary to lift the pump off the floor of the pond to avoid the pond blocking up with dirt and debris - this can be achieved by placing a stone block on the bottom of the pond and placing the pump on top of this. Modern pumps are extremely low maintenance though periodic cleaning of the strainer cage and impellor are recommended for optimal smooth running. Ensure pump is full of water before it is turned on.