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Q. What is a pond filter system?

A. A pond filter system is made up of three main items:
i) Filter- the filter works in two ways, mechanically and biologically. Mechanical filtration means removing the solid particles that cloud the water. Biological filtration means removing pollutants that can be harmful to plants and fish.
ii) U.V.C. - An Ultra Violet Clarifier clumps together the algae that causes green water so that the filter can then remove it.
iii) Pump - A solid handling pump will convey the dirty water into the UVC and filter for treatment. It will also introduce much needed oxygen and stop the fish gasping at the pond surface


Q. How do I install my filter system?

A. Most filter systems are "pump fed". This means that the pump is in the pond, on the bottom as far away from where the water returns as possible and at the deepest point. The U.V.C. and filter are placed together at the edge of the pond connected using the widest bore hose possible to ensure a good flow rate.


Q. Which filter/U.V.C./pump should I use?

A. The deciding factor for choosing which equipment to use is the volume of the pond. The first thing to do is calculate this using the following formula:
Average Length (m) x Average Width (m) x Average Depth (m) x 1000 = Litres

Alternatively go to the Pond Selector page where we will calculate and recommend a system for you.


Q. Do I install the whole system together?

A. To begin with you should not turn on the U.V.C. until the filter is mature biologically. This can take about 6-8 weeks and is the process whereby the filter is colonised by the beneficial bacteria that keep the water healthy.


Q. How long will it take to clear the pond?

Once fully mature, you should notice a difference within one week of turning the U.V.C. on and full clarity should be achieved in two weeks.


Q. How often will I need to clean the filter?

A. You should normally clean 25% of the foams in your filter once every 2-4 weeks in pond water, as long as it is sized correctly and the pond is not overstocked with fish. However, you should only clean the foams when absolutely necessary. This is when they have become completely blocked. The plastic media should not be cleaned as there would be a risk of killing the bacteria.


Q. Will I need to change the foams?

A. A normal cleaning regime, as detailed above, would mean that you will need to change the foams after approximately 3-4 years.


Q. How long does the U.V.C. lamp last?

A. The useful working life of the lamps is 12 months. We would, therefore, recommend that you change the lamp at the start of every season.


Q. What maintenance is required on a U.V.C.?

A. The only thing that needs cleaning is the quartz tube. If there is a build up of limescale on the tube it needs removing so the U.V. light get into the water. This can be done using cleaning agents or even vinegar.


Q. What maintenance is required on a filter pump?

A. A pump will need checking from time to time to make sure it is not getting clogged up by weed. Apart from that it should be run 24 hours a day.


Q. What if the pump breaks down?

A. It is always best to have a standby pump available in the event of pump failure. It need not be as big, it can produce 50% of the flow to keep the filter system running in the interim.


Q. How often should I feed my fish?

A. In summer you should feed twice a day and only feed enough that they eat in 1 minute. Any food left after this period should be removed as it will be too much for them and it will not be digested properly. Fish should not be fed during winter as they become dormant and do not need to eat.


Q. Should I do any water changes?

A. 10% of the volume of the pond should be changed on a monthly basis. This helps control the level if nitrate which, while not being harmful in normal conditions, can build up over a period of months.


Q. The ammonia/nitrite levels in the pond are high - what do I do?

A. The first thing to do is to switch off the U.V.C. This may result in a loss of clarity but it is important to introduce more beneficial bacteria and the U.V.C. can hamper this process. Feeding should also be stopped and Hozelock Cyprio Filter Start added to increase the bacteria level. The levels should then be monitored very closely until they have improved. If the problem is ammonia, then a partial water change of no more than 25% should be done. If the problem is nitrite, pond salt should be added to protect the fish from the effects of nitrite.


Q. Do I run the filter system all year?

A. From a technical point of view, better water quality will be achieved by running all year round. Dormant bacteria will help to "seed" the filter in spring and it will also reduce the risk of the water freezing. However, if there is a U.V.C. in the system, it should be switched off, drained, cleaned and stored in a frost free place. This is because frost can damage the casing and quartz tube.


Q. How do I deal with blanket weed?

A. Blanket weed can be treated in one of two ways. The first option is a treatment such as Hozelock Cyprio Pond Balance. This will kill off blanket weed for several weeks. Alternatively, you can install a magnetic treatment into the filter system. A Hozelock Cyprio Magn-It can help reduce blanket weed to no more than 1" in length.

Should you experience any problems with water quality, or have any questions regarding any of the details given in these pages, you should contact an expert immediately.

Either go to your local aquatics specialist or contact
Hozelock Cyprio UK Helpline on +44 (0)1844 292002,

All of the above details are guidelines and are no substitute for reading instruction leaflets carefully.


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