Velda In Pond Venturi Filter information

The Velda Venturi filter is the latest in pond filter, however Velda have added their own twist to this filter so it does vary slightly to the rest of the all in one filter market. The Velda Venturi doesn't have a built in UVC, so therefore it has been designed as more of an add on to your current filtration system. The idea of the system is that  the Velda Venturi filter sits on the bottom of your pond, then the built in 2500 Lph (litres per hour) pond pump draws dirty water into your filter, then clean water is returned back to your pond. This is the simplified version of how the system works, but I will explain in further detail the importance of pond filtration further on in this review. The key thing we need to know and the unique selling point behind the Velda Venturi is the Venturi, this adds a huge amount of valuable oxygen straight to the biological filtration contained within the filter and helps to provide the best growing conditions for beneficial pond bacteria.

What Is A Venturi?

A pond venturi is a device added to the pond’s pipe-work, which injects air into the pond water as it passes through.

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The laws and concepts of fluid dynamics are quite complex, but the simplified principles related to the ‘venturi effect’ are;

  • If a length of pipe becomes narrower, the velocity of a liquid passing through will increase.
  • As the velocity of the liquid increases, its pressure will drop.
  • If this drop in pressure becomes considerably lower than atmospheric pressure, air can be pulled in from a connected air tube.

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The pond venturi is simply a constricted length of pipe with an air tube attached into the narrowest section. As the pond water enters this narrow section, the resulting difference in pressure sucks in air via the air tube. At the venturi’s outlet, the pipe widens and returns the now aerated pond water to its original velocity as it enters into the pond.

A venturi can only be added onto pipe-work which is attached to a pump, and is therefore normally installed only onto ponds which have gravity fed filter systems.

The aerated water emitted from a venturi can be quite turbulent, sometimes producing an undesired amount of noise or disturbing the pond’s surface. It is a good idea to add a flow control to the air tube, the amount of air taken in by the venturi can then be regulated for when you wish to view the fish, for example.

What Is Filtration And Why Is It Important?

With the Velda Venturi pond filter you are receiving two stages of pond filtration:

Mechanical: Mechanical filtration is the removal of solid waste particles from the pond, these can be as natural as decaying plant matter to less natural debris such as uneaten fish food. The reason why have mechanical filtration is to A) To keep the water clean and clear for aesthetical reasons and B) To stop a layer of sludge forming on the bottom of your pond.

Pond sludge if left can potentially be one of the biggest threats to your ponds health. Pond sludge creates what we call anaerobic conditions (without oxygen) it is here where pathonogenic (disease carrying) bacteria live and thrive. When cultivating these bacteria will release a harmful toxic gas called hydrogen sulphide and this is that rotten egg like smell you may have noticed when cleaning a pond before. In a concentration of more than 0.003 ppm this can start to make the water toxic to your fish, this will lower their immune systems and it is then when the pathogenic bacteria will pass on their diseases to your fish and this will result in conditions such as dropsy which can be extremely difficult to treat. It is for reasons like this and in recent studies it has shown that over 90% of fish deaths are because of initial poor water quality, and this is why it is so important to use as much filtration as possible on your pond.

Biological: To understand biological filtration we first have to understand how the nitrogen cycle works within a garden pond.

  1. In a garden pond we supplement our fish with food, this is then turned into waste which produces ammonia. As soon as we put fish in the pond ammonia is excreted from the gills of your fish as well through its respiratory system.
  2. Faeces and urine then combine with decaying plant mater and then are broke down by Heterotrophic bacteria which turns the waste into ammonia.
  3. Ammonia is now oxidised by nitrosomonas bacteria which will in turn eliminate all ammonia from your pond. This though introduces nitrites into your pond and these are also toxic to fish.
  4. In a similar process the nitrite now needs to be oxidized and this is done by nitrobacter. This changes the nitrites into nitrate, this is still toxic but no where near as bad as either nitrite or ammonia. To keep the levels of this down you need to either water change or by adding plants who use it as a fertilizer.

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All the bacteria that are needed will occur naturally in your pond over time and will cultivate on the sides of the liner and planting baskets etc. However with modern ponds usually having a good stocking of fish, it is vital that we aid the ponds natural bacteria by having a filter that has biological filtration to help give the bacteria other places to cultivate. That is why the Velda Ventrui works so well as an additional filter for the cultivation of bacteria, as air is always being fed straight biological media within the filter, this means strong and thriving bacteria for a healthy pond. When setting up a new pond it is best to help the filter out and uses a filter start treatment, this will add millions of beneficial bacteria to your pond to help it on its way.

How To Set Up And Clean The Velda Venturi

When it comes to setting up and cleaning the Velda Venturi filter we understand that the instructions for product can often leave people confused, so hopefully this series of pictures might help. The first thing you need to do is pull out all three clips on the side of the unit, this will then allow you to pull the green handle and remove the lid from your unit.

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Next you will remove the grey tray which holds the filtra-sub filter medium, for setting the unit up this is where you will pour in the media. If you are cleaning the unit, pour the media into a bucket of pond water (this will be just enough to remove dead bacteria and be abrasive enough for cleaning). You would then be able to hose down the grey basket to clean it of all debris, and once this was done you would replace all the media.

As you will be able to see on the first picture and following on to the second picture below the inlet to your Velda Venturi filter goes straight through a middle section where it meets a small pre filter foam which helps to protect the impeller inside your pump. For cleaning like shown in the picture remove the foam from your unit, then just rinse it in a bucket of pond water until clean.

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Your next job is to clean the large main foams in the centre of your Velda Venturi filter, these two foams like shown in the left hand side picture will just pull out of your filter unit. Once again to clean the foams you will need to rinse them in a bucket of pond water until they are as clean as possible. If you notice that they have become misshaped you will need to replace them, otherwise water is able to by-pass the foams and return to your pond unfiltered.

Even with the pre-filter foam from time to time you might need to remove the impeller of your filter, this can be done really easily. You need to simply turn the impeller cover clockwise (the first time of doing this the cover can be very stiff) you will then be able to pull out and clean the impeller with a cloth and then rinse the impeller housing.

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When setting up your Velda Venturi you will need to make sure you fill the sides with the buoyancy gravel that comes supplied. This makes sure that the unit does not tip over when it's inside your pond, all you need to do is remove the three side pieces that are inside your filter and then pour in the gravel like shown in the picture below.

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