THE PUMPS
A water garden represents an enclosed environment. In order for all living organisms, plants and animals, to survive and all biological functions to take place, it is necessary to continuously supply oxygen, the source of life. Oxygenating plants , such as Elodea or Cerathophyllum, are able to perform this task, but they are not always sufficient and sometimes they cannot be introduced due to the presence of herbivorous fish such as Koi carp. Furthermore, during very hot summers, such as this year, the additional supply of oxygen can solve many problems caused by excessive overheating of the water in our pond. To achieve this, it is necessary to resort to the use of centrifugal pumps. By moving the water, they ensure regular and constant oxygenation , which is essential for the good balance of the tank and the health of plants and fish. To oxygenate, water must come into contact with air. The simplest way is to create a gush that develops above the surface of the pond. But also a waterfall or a fountain they serve to originate turbulence and therefore to enrich the water with oxygen. At the same time the pump can be used to feed a biological filtration system. Whatever the choice, it works in a closed circuit. There is no additional water supply and therefore no connection to the water mains is necessary to maintain the ecosystem we have created.
WHICH PUMP TO CHOOSE?
The choice of the pump must be made according to its flow rate . The head, i.e. the maximum height that the water jet can reach, it must only be considered if we are to feed waterfalls and fountains. All pumps are equipped to feed a jet of water. To feed a fountain, it is necessary to take into account the outlet height of the jet (vertical distance between the surface of the water of the tank and the high point of the fountain) and this distance must be measured. For a waterfall, the calculation is more complex. We must take into account the height and width of the waterfall to be fed. By way of example, for a 25 cm wide waterfall with 1.2 m difference in height (vertical distance between the water surface of the pool and the highest point of the waterfall), a flow rate of 5000L / h is required. We are sure, then, that we have a homogeneous sheet of water from the outlet of the waterfall to the surface of the water. If we have installed a filter, all the water in the tub must pass through at least five times a day. Keep in mind that a filter reduces the pump flow by about 30%. If our tank contains 20,000 liters, you will need a pump that has a flow rate of 6500L / h. If we wanted to feed a filter and a gush or a waterfall, the pump must be able to supply water to all these accessories. Its capacity must be equal to the sum of the necessary capacities each of them has. The adjustment between them can be done with more or less open taps supplied with the accessory set. However, it is never worth saving on pump power. So in the case of the tank of 20,000 liters, with a cascade of 25cm. 1.2m high and a filter, the pump must have a flow rate of 11500 L / h, obtained from the sum of 5000L / h + 6500L / h.
HOW TO INSTALL A SUBMERSIBLE CENTRIFUGAL PUMP
A submersible pump was built to run under water continuously . Under no circumstances must it be operated out of water , under penalty of breaking it. The pump must be placed on a stable base , made of stone or concrete, or on specific supports provided by the companies themselves. It must never be placed directly on the bottom of the pond. The reason is simple: it would get dirty prematurely due to the sediments that settle at the bottom. It can be placed in a container filled with large pebbles that act as a pre-filter. Let’s place it in an easily accessible point of the pond. Before winter, if the pond is less than 50 cm deep, the pump must be removed and placed in a bucket full of water to prevent the seals from drying out. A pump installed deeper than 50 cm can be left in the pond for the whole winter. To ensure total mixing of the pond water, the pump must be placed on the opposite side of the waterfall. To connect it to the latter, we use a large diameter corrugated pipe to limit flow losses.
NOT ALL PUMPS ARE THE SAME
There are two types of pumps available on the market. The first, with a magnetic core, has an impeller that rotates on its axis by means of a steel or ceramic shaft . It takes up the principle of aquarium pumps. It has good performance and low consumption. With this rotor, the impurities contained in the water end up dirtying the impeller. However, the rotor is easily disassembled for cleaning. It is advisable to use a prefilter before the pump body to avoid getting it too dirty. The more frequently you clean the longer the pump remains efficient. This type of pump is suitable for small tanks because the flow rate does not generally exceed 3500L / h. The second uses an asynchronous motor that drives a rotor, a disc with blades . Quiet, it does not need maintenance, but consumes more than the previous one. It is essential to feed a biological filter. In this type of pump the impurities are transported to the filter where they are eliminated. A large mesh pre-filter, to retain the coarsest impurities is more than sufficient and hardly needs cleaning. The performance of the pump thus remains constant over time. For a careful choice, always ask which rotor has the pump you are purchasing.
PERIODIC MAINTENANCE OF THE PUMPS
The pre-filter must be cleaned more or less frequently according to the quality of the water in the tank . It simply needs to be disassembled and passed under running water. Any limescale deposits that form on the impeller can be dissolved by immersing it in vinegar for a few hours. From time to time the sleeves to which the water features are connected must be cleaned with a brush. Pond pumps, designed to work underwater, are perfectly hermetic and very safe. However, great care must be taken in the electrical connection. It may seem like an unnecessary recommendation, but it is good to remember: no connection must be made under water. All connections made outside must take place inside rainproof electrical boxes. The power supply cable will be buried and sheathed to protect it from the clipper and from inappropriate spade strokes. Grounding the power line is mandatory, as is the use of a life-saving device.
