Problem Solving Guide & FAQ's For Pond Keepers & Water Gardeners

This important and useful water gardening web page is structured in the form of a question followed by an answer. All relate to commonly asked questions and pond problems I've solved for people.

For quick reference check these detailed specification tables for most important pond pumps and pond filters.

Biofiltration ... HOW DO I PREVENT MOST BACTERIAL DISEASES IN MY POND?

Excellent biofiltration and feeding high quality food will generally result in few problems with bacterial diseases.
In South Africa and other countries Aeromonas and Pseudomonas bacteria cause ulcer and dropsy diseases. Once the disease is established it is very difficult to eradicate and whole collections of expensive koi can be wiped out. There is one method of prevention and this is by using Viresco a revolutionary natural treatment. This specialised Viresco product can be offered to a casual gardener with pond who will have great success. Viresco is sold in small quantities (5 gm to 25 gm packets) so can be delivered worldwide at the same price.

Biofiltration ... KEEP YOUR BIOFILTER WORKING IF YOU HAVE TO SWITCH OFF YOUR WATERFALL PUMP AT NIGHT TIME.

If you cannot run your waterfall pump at night - for example it may make too much noise - then install a second very small pump that just runs overnight & that will keep water flowing through the filter.
The bacteria in a biofilter die if they are starved of oxygen for more than 5 hours which occurs when the pump is switched off overnight. Once dead the bacteria take between 4 and 6 weeks to become viable again. By installing a low cost efficient pump such as a FOCUS 1200L the filter is kept alive and the flow of water can be diverted direct to the pond without making a noise.

Biofiltration ... WATER REMAINS DIRTY EVEN WHEN A BIOFILTER IS INSTALLED

There are a number of possible reasons for this but the most important is that the mechanical section of the filter is not doing a good job. You need to check if water is able to by-pass the mechanical section - for example are there gaps around the sponges or are there holes in the sponges.
There are a number of possible reasons for a filter not working mechanically this. You need to check if water is able to by-pass the mechanical section - for example are there gaps around the sponges or are there holes in the sponges. If the mechanical section is in perfect condition then algae could be the cause. Algae is not always green and it is so small as to be able to pass through sponges.

Biofiltration ... IMPROVE YOU BIOFILTER 50 TIMES

Replace your present filter media of plastic balls, tubes, and other devices by Alfagrog
Alfagrog is a very porous inert ceramic filter medium. It is produced in England especially for water purification. It is unmatched for effectiveness and value for money. One litre of Alfagrog is sufficient for a biofilter handling 1,500 litres of pond water. Each piece of Alfagrog is full of tiny holes. 1 litre has a surface area of between 40 and 100 square metres for the bacteria to grow on depending on particle size. Compare this with plastic bio media which have a maximum of 1 square metre per litre.

Biofiltration ... WHY DO I NEED A BIOFILTER?

In a swimming pool the sand filter does the job of removing solids and particles that remain suspended in the water. This is filtration namely the removal of solids from liquids. However the filter does not purify or clean the water. This job is done by the use of HTH. In this way it is safe to swim in the water because all the harmful bacteria are killed by the chlorine.
Food is eaten by the fish, is partly digested and partly expressed as a waste product by the fish. The fish needs to urinate and this passes into the water also. Toxic chemicals build up. The biofilter purifies these chemicals. Without the biofilter the fish would poison themselves to death. The secondary reason for a biofilter is to remove solids to allow clear water to be obtained. Its first job however is to purify the water.

Biofiltration ... HOW LONG DOES IT TAKE FOR A BIOFILTER TO START WORKING?

When a new pond is built it will typically take 4 to 6 weeks before the biofilter is working effectively. Therefore during this period introduce new fish slowly.
A continuous supply of oxygen is required to enable the bacteria in the filter to live. This is why a pump must work 24 hours per day since the water is the source of oxygen for the bacteria and without the oxygen the bacteria die quickly and certainly within 8 hours. Once dead the colony takes 4 to 6 weeks to build up again

Fish ... HOW MANY FISH CAN I STOCK IN MY POND?

First of all decide what sort of fish you want to stock You can put more goldfish than koi in the same size pond. The reason is koi eat much more and grow much faster.
If you stock goldfish work on 50cm in total length per square metre of water surface. Work on half of this is you want to keep koi. With excellent biofiltration you can stock about 50% more than this. So in a pond with 2 square metres surface you can stock up to 20 goldfish 5cm long. This allows for the fish to grow. If you want to stock more add 1 to 2 litres of Alfagrog to your biofilter for each 4,000 litres of pond water. It is best to stock goldfish in small ponds.

Fish Food ... WHAT DO YOU MEAN BY 97% DIGESTIBLE FOR KOI FOOD?

As far as koi food is concerned the digestibility is governed by the type of raw material used. If you use high grade raw materials in formulating fish foods then you get high protein and low ash.
97% digestible quite simply means such koi food is an extremely high purity food made from the best raw materials making all the contents of the bag with the exception of the ash and moisture available for the fish's benefit.

Fish Food ... WHAT TYPE OF FOOD IS BEST FOR MY FISH?

Always buy the best food you can afford. This will give you good water quality and fish will grow to their optimum in your pond. Koi Sticks and Pond Sticks are a waste of money. It is far more economical and better to feed floating pellets. Just look at the analysis and you will understand why.
The best foods are those with ash levels of about 5% and moisture levels of about 5-8%. Never buy food which does not give this type of information on the packet. Ash and moisture are a total waste of money. Some foods have a total of ash and moisture = 25%. This means you are only getting 3/4 of a bag of food the rest is rubbish. The type of raw materials used is also very important. Look for herring meal or whole fish meal as the best ingredient and protein levels of 35% or more.

Lighting in Ponds ... ARE LIGHTS IN A POND DANGEROUS?

For superb night time effects install a lighting system in the pond. Underwater lights are very safe since they use low voltage (12V) systems. They are quite low in cost also.
You can have floating globes, underwater spotlights, in ground spotlights, coloured lenses and so on.

Pipes and Fittings ... WHAT PIPE AND FITTINGS ARE BEST TO USE?

Until recently it was only possible to get clear hose or normal hose pipe or to use rigid PVC hose. All these suffered for major disadvantages. Transparent hose and garden hose pipe kink easily. Rigid pipes need expert fitting and are difficult from maintenance viewpoint. It is now possible to buy ribbed hose.
Ribbed hose pipe does not kink and is easy to use and very versatile if used with EasiFitt connections. Do spend a bit more on fittings and hose to reduce your pond keeping hassles. Avoid using jubilee clips which rust and become difficult to remove for maintenance. If you do use clear hose make sure you do not have kinks in the line. This will severely restrict flow from your pump. Avoid sharp bends and minimise the number of connections in the lines.

Pipes and Fittings ... WHAT PIPE SIZES DO I USE IN CONNECTING PUMPS, BIOFILTERS AND UV SYSTEMS?

Always use the largest diameter pipe you can consistent with fittings on the pump or other piece of equipment. The reason is that larger diameter pipe interferes less with flow rate from pump.
If a pump is supplied with a 20mm outlet then use 20mm pipe. If the pipe is to be very long, say 10 metres then it would be useful to install a reducer to increase the pipe size from 20mm to say 25mm. What is important is to reduce pipe length and increase pipe diameter to get the best out of your pump. Do not use 13mm fittings and pipe except on very smalls pumps.

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Pond Treatments ... WHAT CHEMICALS SHOULD I PUT IN MY POND?

None in most cases unless absolutely necessary and you know what you are doing. The absence of a filter is more often than not the reason people add chemicals.
When the situation is reached that chemicals are to be added to a pond then this should only be done under guidance. It is rarely necessary to treat pond water. Some exceptions are when it is important to start up a filter from scratch then a bio starter can be used. These are non chemical and are perfectly safe to add. Another time is if you get blanketweed One remedy for this is Biotal All Clear.This is a natural product which can do no damage.

Ponds ... I WANT A POND BUT I AM NOT SURE OF MANY THINGS. WHAT DO I DO?

Nothing until you have spoken to a reliable source of information and products.
If you are not sure ask someone who can give you good advice. If the advice is sound and makes sense and can be backed up by example or published information then it is probably good advice. However if something does not make good sense to you maybe seek further advice and certainly probe the advice given. A bad installation is expensive to fix.

Ponds ... WHAT IS IMPORTANT TO LOOK OUT FOR IN INSTALLING A POND?

The pond installation is the most cumbersome and therefore the most difficult part of the total project so do your best to get this right. Seek help if you do not feel comfortable with doing the job yourself. Most important do not rush it - take your time, get it to fit well into the hole, create good back fill and edging support where necessary.
For preformed pond installation TAKE trouble to get the pond levelled. If you do not the pond will certainly appear lopsided once the water has been filled into it. Use a sprit level. For larger ponds use black plastic liner designed for pond building. Look for a 15 year or more guarantee and get the surround level.

Ponds ... WHAT DOES A COMPLETE POND COST?

This is an impossible question to be answered simply. As a general rule however rather spend more on a small pond than go for a larger pond and skimp on equipment.
A very beautiful pond including all necessary equipment can be created within a day by unskilled people choosing the DIY approach for a cost of around R1,500 for a small 300/400 litre pond to about R3,000 for a pond of about 5,000 litres. Such ponds will incur minimum running costs and will involve very little maintenance if the ideas in this publication are understood and followed. It is not vital that the brand of equipment we sell is used so long as good quality alternative equipment is specified.

Ponds ... WHAT PRECAUTIONS MUST I TAKE IF I INSTALL A LINER POND?

The fundamental potential problem lies with the fact that a liner is relatively thin at between 300 and 500 microns. Avoid complex shapes. Do not worry about the liner pleats that will inevitably remain in the pond.
If you are going to build a liner pond the before placing the liner in the excavated hole it is important to line the hole with old carpet, underlay, newspapers or something like this to prevent stones finding their way to the interface with the liner and possibly puncturing it. If you have dogs that like swimming then a liner pond can be bad idea since clawing the liner will inevitably damage it.

Ponds ... WHAT IS BEST TYPE OF POND?

The best type of pond is the one that suits your idea in terms of size and appearance. The choices are black plastic liner, and rocklike fibreglass ponds and concrete ponds.
Unless you want a really big pond to keep and grow big koi avoid concrete. These ponds are expensive to do properly. For smaller ponds of up to 800 litres choose pre formed fibre glass. These are simplest to install and also low cost. Plastic liners are cheapest of all and very suitable for designs of your choice.

Ponds ... HOW DO I KNOW HOW MUCH WATER IS IN THE POND?

Record how much water your pond holds - you will need this information to specify a number of products and also for future reference. Store the information safely unless you can recalculate the volume yourself.
If your pond is square or rectangular and is the same depth throughout it is very simple. All that is required is to multiply the length by the width by the depth. To calculate the volume of water in the pond in litres use metres to measure the dimensions and multiply the result by 1,000. For example for a pond of 3 m length * 2 m width * 0.5 m deep the volume of water it can hold is 3,000 litres of water. If your pond is not a simple rectangle or square then you have to approximate.

Ponds ... WHAT IS THE BEST LOCATION FOR MY POND?

Your pond should be sited so you can enjoy it, you should be able to see it easily, be able to sit close to it.
Full shade should be avoided, whilst partial shade is a good idea from the fishes point of view. Do not put the pond close to deciduous trees if you can avoid it because of falling leaves in autumn. Your pond should be sited so you can enjoy it but don't put it outside the bedroom window unless you like the sound of running water to get you to sleep. The reason is because your biofilter needs running water 24 hours a day and the gurgling/splashing sound might just annoy you as you lie in your bed.

Ponds ... WHAT IS BEST ADVICE YOU CAN GIVE TO THE CUSTOMER BEFORE GOING AHEAD WITH BUILDING A POND?

They presumably want to keep fish and have a feature in their garden they would prefer to enjoy than grumble about.
Without a doubt install a good biofilter and Ultra Violet lamp system. It goes without saying that you need a pump correctly specified.

Pumps ... WHAT DOES MAXIMUM HEAD MEAN?

This bit of information means at that head or height difference between the water surface and the waterfall the flow from the pump will be 0 litres per hour - i.e. there is zero flow.
This information should be ignored or used to compare one pump to another. This information has mislead many people into buying the incorrect pump. It is important to know how much water the pump can handle at different practical heads or height differences between the water surface and the waterfall inlet for example.

Pumps ... IS IT BEST TO BUY A CHEAP PUMP OR AN EFFICIENT PUMP SPECIALLY MADE FOR POND USE?

The majority of retailers who sell pumps will never mention the advantages of low power consumption pumps yet this is a very important part of a purchasing decision. I would go as far as to say that the concerns over running costs could outweigh those concerning the cost price.
A top selling pump in South Africa which costs about R1,200 uses R700 per year in electricity and has a 1 year guarantee. After 3 years this pump if it has not had to be replaced has cost R2,100 in electricity and R3,300 in total. The FOCUS pump that would satisfy by far the majority of applications in which the larger pump would be used would cost less with an electricity cost of R100 per year. It would also carry a 2 year guarantee. After 3 years the purchaser would have saved R1,800 minimum.

Pumps ... HOW DO I KNOW HOW MUCH WATER MY PUMP MUST HANDLE?

As a basic rule of thumb a pump should pump the total volume of the pond every 2 hours. In this way the contents of the pond are circulated 12 times a day. At this flow rate there is a good balance between the needs of plants, fish and the biofilter in a pond system. You may want to pump more than this if you want an impressive waterfall effect.
A pond of volume 5,000 litres would be happy having a pump flow rate between 2,000 and 4,000 litres per hour. A pond of volume 2,000 litres would be happy having a flow rate between 700 and 1,600 litres per hour. The important point is to get the flow rate somewhere between one third and about two thirds of the pond volume for a good balance. What is more important is that if your pond is say 1,000 litres you certainly do not need a pump that can do 5,000 litres per hour

Pumps ... HOW CAN I TELL IF A PUMP IS SUITABLE FOR USE IN A POND?

Pond pumps are designed to operate in harsh outdoor environments. In practice this means the water in which they reside becomes polluted. Foreign objects find their way into the pump moving parts and can do damage if the pump is not designed to withstand these rigours.
it is illegal to sell an outdoor pump unless there is at least 10 metres of 3 core cable attached to it. The box and if not the box the label on the pump itself will indicate indoor or outdoor ( a small sign showing picture of house with arrow pointing into the house indicates for indoor use only). The pump will have 2 or 3 year guarantee period. If any of these are missing do not buy the pump for use in a pond.

Pumps ... WHY IS THE GUARANTEE IMPORTANT?

A 2 or more years guarantee tells the customer especially when it comes to pond pumps that the design is good, the performance good, and that the manufacturer stands behind his products.
A pond is a very harsh environment in which a pump has to run 24 hours a day 365 days a year. When you see a 2 or more years guarantee on a pump you can buy with total confidence. Beware of Sump pumps. These pumps are powerful and large - they stand upright and are thus easily recognized. Sump pumps are designed to run for a certain amount of hours and since they are primarily designed for intermittent running their life span can be considerably shortened when run continuously in a pond.

Pumps ... HOW TO SELECT THE CORRECT PUMP?

Selecting the correct pump is critically important. Apart from doing the job you want it will last you a long time and running costs will be very low. If you want a waterfall and no fountain choose a pump which does not need a sponge on the suction side of the pump. This saves a lot of maintenance. Do ask us for advice if you are not sure.
Many pumps sold in South Africa are not suitable for ponds. You can tell a pond pump very easily. It will have 10 metres of 3 core cable and the box will tend to be larger. There will be a guarantee of at least 2 years - DO NOT buy 1 yr. guarantee pumps for ponds. They do not last. You need to specify how much water in litres per hour you want to pump and to what height this quantity must be pumped. A pump using 100 watts will cost R200 Rands per year to run.

Pumps ... WHAT DO PEOPLE MEAN WHEN THEY TALK ABOUT THE HEAD OF A PUMP?

This is a fancy word for what pressure can the pump develop. In other words how high can it pump.
Head is the height difference between the water surface in the pond and the outlet point of the pipe attached to the pump. If the outlet pipe from a pump was lifted 50 cm above the pond surface then a certain amount of water would flow out of the pipe. If the pipe was then lifted to 1 metre above the surface of the pond then a reduction in flow would be seen What we now see is that the higher the head for the pump then the lower is the amount of water pumped.

Pumps ... WHAT DOES MAXIMUM FLOW MEAN?

Maximum flow is the absolute maximum water the pump can handle.However it is only able to pump this amount with no pipe attached to it. It is an impractical indication of pump usefulness.
This information should be ignored or used for comparison only. It has mislead many people into buying the incorrect pump. It is important to know how much water the pump can handle at different pumping heights.

Pumps and Fountains ... I MUST HAVE A FOUNTAIN IN MY POND

If you need to run a fountain in your pond it normally makes good sense to select a pump that comes with these fittings.
Most FOCUS pond pumps are supplied complete with fountain attachments. If you buy the fountain attachment later it may be expensive. On the other hand there are some very impressive fountains which might appeal to you. If you want to run both a waterfall and a fountain make sure your pump is powerful enough. You must run the pump with the sponge in the suction to prevent the holes in the fountain blocking with debris. The bell fountain is a very popular design.

Pumps and Waterfalls ... DO I NEED A WATERFALL?

It is a good idea to have a waterfall for the following reasons:To hear running water, to add character to your pond feature, to add oxygen to the water for the benefit of the fish and the biofilter and to use the soil that came out of the ground when you installed the pond.
A waterfall with a wide lip will need more water than one with a narrow lip to create a good effect. In my experience the fibre glass rock-like waterfalls are perfect for most garden ponds and are well designed to handle the appropriate water flow for the size of the waterfall itself. Very few garden ponds benefit from a waterfall as high as 1 metre and even this is probably too high unless a cascade effect rather than a fall effect is required. An ideal height for a waterfall is between 40 cm and 60 m.

Ultra Violet Clarification ... PREVENT YOUR WATER FROM GOING GREEN

Install an Ultra Violet Clarifier of correct wattage for your size of pond. 8 watts is normally big enough for a pond up to 5,000 litres.
Water goes green because the algae which feeds on nutrients in the water provide it with food. This together with bright sunlight can happen very suddenly. Because algae is very small (4 microns) it is almost impossible for a normal filter to remove it. If water containing algae is passed through an Ultra Violet clarifier the algae are killed and they clump together making it possible for them to be taken out in a good biofilter.

Ultra Violet Clarification ... DOES AN UV CLARIFIER UNIT NEED ANY MAINTENANCE?

Ultra violet clarifiers (UV for short) have been one of the best inventions ever for the pond keeper but surprisingly only a very small percentage of pond keepers know of their existence.
One very important maintenance point has to be made. The UV lamp inside the quartz tube has to be replaced after about 8,000 hours use which is every year in practice. This is a must because the lamp is useless after this period. The best time to install a new lamp is August in South Africa. So if your pond starts to go green even if the 1 year is not up it is probably time to replace the lamp in your UV unit