Air pump

Why has the amount of air delivered by my pond aeration system dropped off?

The membranes in the air pump can wear. They should be replaced annually to maintain the air flow and maximise the lifetime of the pump. New parts can be purchased easily at your retailer or online. Find a retailer here . You should also check to make sure that the air hose is not being pinched off or squeezed.

Algae

I have a Clear Control 50, but I still have a problem with floating algae. What should I do?

Regardless of which filter you use, green water (containing floating algae) should turn clear with a UV-C filter. This approach will not work only when the pond is old, with a lot of organic material on the bottom and an acidified environment.

The effective lifetime of a UV-C lamp is approximately 7500 hours. When used continuously, the lamp will therefore last for a pond season. You should replace the lamp every spring.

In addition, it is advisable not to have too many fish in the pond.

What can I do to stop fibrous algae?

A short-term solution is to use AllClear or Alglets. You should bear in mind that this will not help in the long term.

Green fibrous algae are actually aquatic plants as well, but with a simple structure. Even so, they can be enormously invasive and bond large amounts of nutrients.

The long-term solution is to introduce more marsh plants and water lilies: cover 30-40% of the water surface with floating plants. The aquatic plants absorb the nutrients and slow down algae growth. Make sure the general hardness (GH value) of the water is at least 12°DH. Regularly remove as much of the fibrous algae as possible from the pond. As your plants grow and increase in size, the growth of the fibrous algae will be slowed down: the primary growth of these algae will, in time, be taken over by the growth of the aquatic plants.

A T-Flow Tronic, an electric system for tackling fibrous and slime algae, is a guaranteed solution for the long term.

Bottom sludge

I have a problem with sludge on the bottom of the pond. What should I do?

If you have a lot of problems with sludge on the bottom of the pond, we advise Bio Oxydator. Bio Oxydator removes sludge on the bed and prevents the formation of new sludge.

Carbon dioxide

What is carbon dioxide exactly and why is it important?

Carbon dioxide (CO2) is vital for the growth of aquatic plants. If there is enough CO2 available in free form for aquatic plants, they can grow well, converting organic matter using light and releasing oxygen. This is known as ‘assimilation’. Incidentally, CO2 levels fluctuate during the daily cycle. Underwater plants absorb CO2 using light and then release oxygen. As a result, CO2 levels fall during the day. At night, the process is reversed: the plants absorb oxygen and release CO2 (albeit to a limited extent)

Micro-organisms, the largest producers of CO2, are active throughout the daily cycle. As a result, CO2 will accumulate at night and levels will fall significantly later in the afternoon. This process only occurs in water bodies that function properly. In other words, when there are underwater plants growing and when the micro-organisms are active enough. We can monitor this process using the pH value. If the pH value is relatively low in the morning (pH 7-8) and relatively high in the evening (pH 8-9), the pond environment is functioning properly. The plants will grow well and the water will be clear. However, an unchanged pH (9 or higher) in the morning and evening indicates stagnation: the underwater plants are not growing and the pond is full of algae. The pH will fall after the growing season. The growth of aquatic plants (and algae) stagnates and so they stop absorbing CO2. The CO2 level in the pond will gradually increase. If the GH value (see GH chapter) is high enough, the excess CO2 can bond to form carbonate and the water will not acidify. The pH will not fall below pH 7. However, if the GH value is too low, there will not be enough calcium to bond the excess CO2. The water acidifies and there will be an oxygen deficiency. The pH value in this case will fall to below pH 6. You can use a simple Aqua test set to determine the pH very accurately

Fish

What is a good number of fish for my pond?

The rule of thumb for the number of pond fish is: 50 cm of fish length per 1000 litres of water. That’s 10 to 12 fish in a 5000-litre pond. This number limits the burden on the pond environment because too many fish in the pond will dirty the water and deplete the oxygen level.

My fish are gasping for air. What should I do?

Gasping for air can indicate a shortage of oxygen. A quick fix for oxygen problems is to replace the water and to buy a powerful air pump that gets water circulating well, particularly in the lower layers. We have a wide range of pumps and air pumps in our range that raise oxygen levels. You should also make sure you have a wide range of oxygen plants in your pond.

Green pond water

My pond water is very green. Is it best to use Crystal Clear or Alglets?                       

Crystal Clear is a solution for green water (floating algae). Alglets combat fibrous and slime algae. However, they don’t tackle the root cause and new algae may form again quickly.

A UV-C Filter is a highly suitable way of tackling green water permanently.

My pond water is very green. Is it best to use Crystal Clear or Alglets?

Crystal Clear is a solution for green water (floating algae). Alglets combat fibrous and slime algae. However, they don’t tackle the root cause and new algae may form again quickly.

A UV-C Filter is a highly suitable way of tackling green water directly and providing a permanent solution.

My pond water is still green, even though I have cleaned the filter and replaced the lamp. What should I do?

Green water means that there are floating algae in your pond. Your filter and UV-C lamp may not be able to cope with the amount of water. A good rule of thumb is: an 18 Watt UV-C filter should be enough to keep a pond of up to 20,000 litres clear.

In addition, you can try giving your fish a little bit less feed for a few days. There may be too much feed, and that results in more algae.

My pond water is green, what should I do?

If your pond water is green, then it is very likely that algae are the problem. You should first identify the type of algae in the pond. If green particles are floating in the water, the problem is floating algae. A short-term solution is to use Velda Crystal Clear. Crystal Clear is an environmentally friendly product that gets dirt and algae to settle on the bottom and makes the water clear.

The long-term solution to this problem involves several steps. Apply a layer of substrate if there is none present. At the same time, add Bacterial (nitrifying bacteria cultures). Put more pond plants into the water. At this stage, floating plants such as nymphoides peltata, frogbit, Azolla, duckweed or water lilies are a good choice. Make sure the general hardness (GH value) is high enough. This should be at least 8°DH. If the value is lower, use Velda GH-Plus to raise it.

If you take all these steps, the environment will stabilise after a while and the floating algae will disappear. Once the water is clear, you can put in the oxygen plants. Good varieties are elodea, hornwort and pondweed. Another excellent way to improve the environment and make the water clear is to install the Cross-Flow Biofill. Velda guarantees a clear pond within three months with this product.

Guarantee

Am I entitled to a guarantee?

Velda guarantees that all its technical products will work properly for a period of two years after purchase. If you register your purchase for a guarantee with Velda, we can process your application faster if there is a problem or malfunction. Keep the original receipt and report the defective product where it was purchased to claim your guarantee. See also the guarantee conditions.

How long is my guarantee?

If a Velda product does not work properly, you can of course invoke our guarantee conditions. Velda guarantees that all its technical products will work properly for a period of two years after purchase.

How can I see whether I have a guarantee?

Go to our guarantee registration page on our website where we describe the steps you need to follow to see if you have a guarantee.

Pond maintenance

My pond is completely frozen. Is that a problem?

Fish are often killed when ponds freeze, particularly small shallow ponds. However, you should never chop a hole in the ice because the vibrations will harm your fish. Aeration of the water is a better solution. The air bubbles keep the pond ice-free and the water rich in oxygen. You can also purchase a pond heater.

There are a lot of autumn leaves in my pond. Is that a problem?

Yes, sedimented organic matter contains nutrients for algae and it can cause explosive algal blooms in spring. Remove fallen leaves with a net and place a net over the pond to keep out leaves and twigs.

Pond pump

Why is my pond pump delivering less water?

A reduction in the water output from the pond pump can be caused by:

  • Dirt accumulating in the housing. Clean the pump parts and do not place the pump in the mud on the bottom, but on a raised section (of stones).
  • A blocked outflow. Use the largest possible hose diameter, saw off the unused part of the hose socket and make sure the water flow isn’t being pinched off. If the water has to bridge a height difference, the net flow will be reduced.
  • A dirty or worn rotor. Open the pump and remove the dirt near the rotor or replace the rotor itself. New parts can be ordered easily at your retailer. Find your nearest retailer here. 

Pond sheeting

How much pond sheeting do I need for my pond?

The simplest method is to make a drawing of the pond and then to measure the pond with a tape measure. You can then use the following simple calculation:

  • Length = pond length + 2 x depth of pond + 2 x 70 cm
  • Width = pond width + 2 x depth of the pond + 2 x 70 cm

Enter the sizes you obtain in this way in the drawing. The garden centre or pond specialist can then calculate for you how much pond sheeting you need.

Soil substrate

Why is a soil substrate important?

Pond substrate consists of porous stone full of microscopically small spaces in which the bacteria that purify the water settle and propagate. These useful bacteria break down organic waste and maintain the biological balance in the pond environment. A dose of Bacterial accelerates this process.

UV-C lamp

The UV-C lamp isn’t working at full strength. What’s going on?

The UV-C PL lamp works optimally only after a week or two. This is normal for this type of lamp. When used continuously, the effective lifetime of the UV-C lamp is approximately one year. You should preferably replace the lamp in spring and clean the quartz glass as well. New parts can be ordered easily online or at your retailer. Find your retailer here

Velda Products

Cross Flow Biofill: which pond pump do I need?

In combination with the Cross-Flow Biofill, we advise the Green Line pump 5000. It consumes very little energy and it has a long life.

If another pump is present, we recommend the following:

Velda advises a maximum capacity for the Cross Flow Biofill so that the filter will not be overloaded and leak. The following conditions apply:

  • The water must be able to flow freely out of the filter.
  • The diameter of the outlet must not be reduced.
  • The water must not be pumped upwards.

The net pump capacity depends on the distance and height of the pump with respect to the filter. If the water has to cross a large distance and height, the net capacity will be significantly reduced.

If the capacity of the pump is too large, you can reduce it by placing a T-connector that allows some of the water to flow directly back into the pond. You can regulate the flow of water by adjusting the outflow diameter in this connector.

My Velda product does not work properly. What can I do?

If a Velda product does not work properly, you can consult the user instructions or send us a question using WhatsApp to +31620613424 or by email to service@velda.nl. Replacement parts such as filter materials, UV-C lamps and hose sockets can be ordered easily at the retailers near you. Find them here

AllClear: if I use it, can I leave my filter and UV lamp on?

Yes, you can! Neither the filter nor the UV lamp affect AllClear.

Cross Flow Biofill: the lid is bulging. What’s going on?

This is because the Cross-Flow Biofill is not a pressure filter and so you should prevent excessive pressure build-up as a result of the clogging of the filter.

The water is not flowing as it should and so the lid is bulging. Regular rinsing of the filter material will solve this problem.

T-Flow Tronic displays error code 1 and 99 or -99 degrees Celsius. What should I do?

If the T-Flow Tronic displays the wrong temperature, the plug is not making a proper connection. It is very likely that the plug has not been placed in the right position. The solution is to take out the plug and plug it in differently to improve the connection.

Cross Flow Biofill: can it be combined with another pump?

Velda advises a maximum capacity for the Cross Flow Biofill so that the filter will not be overloaded and leak. The following conditions apply:

  • The water must be able to flow freely out of the filter.
  • The diameter of the outlet must not be reduced.
  • The water must not be pumped upwards.

The net pump capacity depends on the distance and height of the pump with respect to the filter. If the water has to cross a large distance and height, the net capacity will be significantly reduced.

If the capacity of the pump is too large, you can reduce it by placing a T-connector that allows some of the water to flow directly back into the pond. You can regulate the flow of water by adjusting the outflow diameter in this connector.

Bio-Oxydator, can an overdose harm the fish?

Bio-Oxydator is not harmful for your fish, plants or pond. Bio Oxydator contains a water hardening agent (including lime) to make the water on the bed slightly harder, and a bacterial culture to break down organic waste on the bed.

This product has been in the Velda range for a long time and it is not harmful, even in excess dosages.

Cross-Flow Biofill, the lid doesn’t close properly and it leaks. What should I do?

A leak in the Cross-Flow Biofill is almost always due to pressure build-up or a larger amount of water going through the filter than the filter can handle. This is not a pressure filter and so that should be prevented. There are a few points you should check if the Cross-Flow Biofill leaks:

  • Check whether the filter material is clogged or contaminated. Particularly if your pond is very green, the filter material will get contaminated quickly and require rinsing. Keep doing this regularly until the pond is clean.
  • Check to make sure that the partitions are well placed with the flow openings in the right place and the notches at the top. You can also make these notches larger.
  • The filter materials should be positioned in accordance with the instructions: the coarse filter material (Japanese mats) must be in the second chamber.
  • The filter outflow orifice must be 50 mm and should not be reduced in size. The water must not go upwards after leaving the outflow since this will result in too much back pressure on the filter.
  • Try removing the filter materials one by one to see if the filter is still leaking.
  • In theory, the Cross-Flow Biofill can work without a lid (for testing purposes) without overflowing on condition that the filter is not clogged. If it overflows, you should reduce the amount of water being delivered by the pump.

The maximum flow rate for the Cross-Flow Biofill is 5000 L/h. The filter cannot cope with a higher net flow from the pump and it will leak. You can reduce the net flow from the pump by placing a T-connector in the hose and letting some of the water flow directly back into the pond. The distance from the pump to the filter, and particularly the difference in height between the pump and the filter, will affect the net flow from the pump. The larger they are, the lower the flow from the pump.

Check whether the ring in the edge of the lid is positioned properly. Don’t forget that this ring can cope only with low water pressures. Leaks are less likely if the Cross-Flow Biofill is positioned above the water level.

Clear Control in use, but I still have a problem with floating algae. What should I do?

Regardless of which filter you use, green water (containing floating algae) should turn clear with a UV-C filter. This approach will not work only when the pond is old, with a lot of organic material on the bottom and an acidified environment.

It is important to replace the UV-C unit every two years. In addition, it is advisable not to have too many fish in the pond.

I-Tronic: is this device safe for the pond and the fish?

The I-Tronic releases copper ions into the water by electrolysis. During electrolysis, there is an electric current from the anode to the cathode. An electric current, just like water, chooses the shortest and easiest route from A to B. It is not true that this current can make a detour through the pond and so there is no charge in the water.

It is well-known that copper ions inhibit algal growth at a concentration of 0.2 to 0.3 ppm (or 0.2 to 0.3 mg per litre of water). The European Drinking Water Directive states that there is no risk for people and animals, even at a copper-ion concentration of 2 ppm, with the exception of invertebrates such as snails and mussels. There are no test results indicating that the prolonged addition of copper ions in the low concentrations used by the I-Tronic is bad for fish.

Many of the stories found on Internet forums relating to fish deaths that are supposedly caused by the I-Tronic are simply mistaken, some are due to disease and some are related to the I-Tronic being used for the first time in the season, in combination with low levels of oxygen and/or the setting being too high.

Every product for algae involves a certain risk for plants and animals if they are not used correctly or if the dosage is wrong. Fibrous and slimy algae, like oxygen plants, release oxygen into the water. Especially at high temperatures and if the level of oxygen in the pond is low, oxygen levels can decline too far if you eliminate the algae too drastically. In effect, you remove a source of oxygen from the water and so your fish may die. So it always makes sense to keep the I-Tronic setting low at first, and then to gradually raise it and aerate the pond and/or to replace some of the water with tap water to maintain a high level of oxygen.

I-Tronic: there is a brown deposit on the stainless steel housing of my I-Tronic. Should I remove it?

The I-Tronic works better if it is cleaned regularly. The stainless steel sleeve in the green cap covering the copper anode must be cleaned. Regular cleaning of the copper anode and the contacts in the screw cap will help the I-Tronic to work better.

I-Tronic doesn’t work and there are still algae in my pond. What can I do?

Check the following if the I-Tronic isn’t working after you install it:

  • There should be no activated carbon or zeolite in the filter.
  • The water flow for the IT-05 and IT-15 must be at least 3000 l/h, and 5000 l/h for the IT-35 and IT-75.
  • The red LED light should light up during use.
  • All the times must be programmed in the device.
  • The device destroys fibrous and slime algae but not floating algae (green water).
  • The device must be mounted horizontally.

For more information and the instructions, click on the following link for the I-Tronic

Cross Flow Biofill: which pond pump do I need?

We advise the Green Line pump in combination with the Cross-Flow Biofill. It consumes very little energy and it has a long life.

I-Tronic error code “system error” and “anode failure”. What should I do?

This error message usually appears only if there is no anode in place or if there is a conductive obstruction in the I-Tronic. The water may be very conductive, and this will disrupt the current from the anode to the cathode.

You should take the I-Tronic out of the pond and turn the power off. The I-Tronic should then work again normally. If not, you should talk to your dealer.

Crystal Clear: I have put it in the pond but the water is still green now, six hours later. What should I do?

Crystal Clear is not effective if there is too much movement in the water, which makes bonding impossible. Excessive dissolved substances in the water can also have a negative effect. Replacing some of the water is a good remedy. For example, change 25% of the water and do the same thing again every 2 to 3 days (three times in all).

Crystal Clear is a short-term solution for green water (floating algae). The product bonds the algae (by forming flakes) and the water becomes clear again. However, it doesn’t tackle the root cause and new algae may form again quickly.

Clear Control: Does it have to stay on for the whole year?

We recommend turning the filter off in the winter to prevent damage due to freezing. The filters should stay on day and night the rest of the year.

A bacterial culture is created in the filter that keeps the water clean, while the UV-C lamp kills the algae. The bacteria die when the filter is turned off for a few hours and the culture has to be created again when the filter is turned back on.

I-Tronic error message “Check electrode current to high ERROR 2” for T-Flow

Excessive conductivity of the water is less common. If the level of dissolved conductive substances such as salt is too high, the conductivity of the pond water should be reduced.

The solution: replace some of the water (approximately 1/3 of the pond content) to reduce conductivity.

I-Tronic error message “Check electrode current to low, ERROR 1” for T-flow

If the solutions listed in the manual fail to resolve the problem, the cause in many cases will be the lack of conductivity in the pond water, which is often due to a low GH. A minimum GH value of 8° will be required to stop the error message. The solution: raise the GH value by adding a salt solution. Add a little bit of salt to a cup of water. Then put the end cap with the cable, the copper anode and the stainless steel cathode in the salt solution. If the error message persists, add GH plus from Velda to increase the conductivity of the water.

Water plants

How should I place water plants in my pond?

After purchase, put the pond plants immediately into plant baskets that are about 30% larger than the cultivation pots. Use a liner in coarse-meshed baskets. Fill the baskets with a special growing soil that is tailored to the requirements of the plant and cover the soil with a layer of pond gravel. Lower the baskets slowly into the pond and place them at the correct depth (indicated on the label).

What is a good number of plants for my pond?

The guideline for 1000 litres of water is: 5 bunches or 3 pots of oxygen plants + 6 marsh/waterside plants. A 5000-litre pond, for example, can accommodate 10 bunches + 9 pots of oxygen plants and 6 groups of 5 marsh/waterside plants.

You can add 1 or 2 water lilies depending on the size of the pond, and as many floating plants as you wish. At least 50% of the pond surface should be covered with water plants for a healthy pond.

My oxygen plants are not growing well. What should I do?

There are a number of possible reasons. The oxygen plants may not be getting sunlight, they may be too deep in the water or the hardness of the water may not be right. Make sure your oxygen plants are at the correct depth and that they are getting sunlight for at least six hours a day. You should also check the hardness of the water. If it is too low, use GH Plus to raise the hardness.

If there is green algae in the pond preventing sunlight from getting to the oxygen plants, you should fix that problem first.

My water lilies are not growing well. What should I do?

There can be several reasons to consider. The water lily is too deep, too close to a pump or waterfall, in a basket that is too small or in the wrong type of soil.

If it is too deep or too close to a pump or waterfall, you should move the lily. If the basket is too small, put the lily in a larger basket and fill the basket with special soil or substrate for water lilies.

Don’t forget that water lilies bloom late in the season, especially the flowers.