Let's talk about pond pumps for your water feature.
In a large lake high winds do the job of a pump. These winds circulate the water and mix it very thoroughly. Through the actions of waves life-giving oxygen is added to the water and pollutants are mixed with the body of water in order to dilute the toxic effect resulting from fish waste and other contaminants.
Any body of water, small or large that is not circulated will become stagnant very quickly. Stagnant water becomes a breeding ground for pathogenic bacteria of all sorts. These bacteria kill fish and create smells.
A pump is therefore very essential in any garden pond.
In South Africa I am sure that most people when they buy a pump get poor advice and end up buying a pump which is unsuitable for the job. In choosing a pump there are very important factors to consider.
-
How much water will the pump handle under the conditions pertaining to your own pond?
-
How much pumped water is ideal for my pond?
-
How much money will it cost to buy?
-
How much money will it cost to run?
-
How reliable will the pump be?
-
How will my problems be handled if the pump fails?
-
How can I save money and still achieve all necessary functionality?
Consider each of these items in turn:
1. For 99% of garden ponds the pump you choose you should be submersible and NOT the swimming pool type. When you submerse the pump in the pond keep it off the bottom by placing the pump on a brick or something similar. In this way dirt from the pond bottom is not sucked into the pump.
2. Place the pump where you can EASILY get to it for maintenance purposes (number 1 priority) and also in such a way to minimise the length of pipe from the pump to the filter or waterfall.
3. Make sure the electrical connections are made safely. All outdoor pumps must have 10 metres of cable attached to them. Do not accept any pump for outdoor use unless it has 10 metres of cable. We are talking safety here. Do not lift the pump using its cable - tie a sting or wire to pump if you need help in lifting the pump from the bottom of the pond.
4. To choose your pump you need to know how much water you want to pump and to what height above the water surface you want to pump the water - notice I said from water surface and NOT the bottom of the pond. These two variables we call Volume flow rate and Head respectively. These are normally expressed in litres per hour and metres.
Any submersible pump can handle various combinations of flow and head. Think of it this way - the motor on the pump pushes out a fixed quantity of energy. It can use this energy to pump less flow to a higher level OR more flow to a lower level.
Be careful when you see maximum flow and maximum head readings on a pump box. The pump cannot do maximum flow and maximum head at the same time. In fact maximum flow occurs when head is ZERO. Conversely maximum head occurs when flow is ZERO.
5. For most ponds the desired flow rate and this is a flow rate that will suit plants, fish, biofilters, UV lights and anything else in the pond is about half the pond volume every hour. If your pond is 3,000 litres then your pump should push out about 1,500 litres per hour. In this way the contents of the pond are turned over 12 times every day. It does not matter if the flow is a bit more or less. If you pump too much you just waste money since the more flow and/or head the larger and more expensive the pump in terms of initial cost and running costs. The only good reason for pumping more water is if you want to create an impressive waterfall - please remember we are talking in these articles about smaller garden ponds and not large koi ponds.
6. Now you know how much water to pump then all that is left is to decide how high you want to pump the water. If you have a waterfall then this height is measured from the pond water surface (not the bottom of the pond remember) to inlet point to the waterfall.
7. Knowing these two variables selection of the right pump becomes much simpler. In addition to these items, forgetting cost for the moment, check to see if the pump has additional features such as valves and fountain jets that may be included with the pump. These items can be expensive when bought later. If you do have a fountain then this will result in less flow going to the filter. Consequently if you want a fountain and a waterfall you might want to go for a somewhat larger pump.
8. You can refer to the information on most pump boxes. If you cannot find this information then do not buy the pump. If you have doubts go one size larger in your final selection.
9. Pump costs - most people only ever consider the purchase price of a pump. I have yet to meet a retailer who has ever mentioned running cost in advising pump selection yet in most cases this is far more important than the initial purchase price.
South Africa ONLY: You can check how much per year the cost will be to run your pump - look at the watts consumed (should be on box) and multiply by 2.6 This will give you a good estimate. If you do not see the watts power consumption do not buy the pump.
10. Always buy a pump for a pond with at least a 2 years guarantee. If the pump has less than a 2 year guarantee DO NOT USE IT IN A POND.
12. For no hassle guarantee performance buy reputable pumps from reputable retailers. If you do not get sound common sense advice and if the retailer does not understand what you now know then consider going elsewhere to buy your pump.
To learn a great deal about pond keeping and get a free book go to http:///www.practical-water-gardens.com subscribe to the Water Gardens Gazette and you will be provided with link to a free introductory 25 page book about pond keeping that you will be able to download immediately