Ponds are a source of great pride for many gardeners. Not only do they create a sense of tranquillity in the garden, they also attract wildlife and give us the opportunity to keep beautiful fish.
Pond water needs to be constantly circulating, otherwise it will stagnate.
Pond pumps help keep the water moving whilst filtering and cleaning it. They remove debris and clear the water, whilst oxygenating it and improving the conditions for the plants and fish.
The best pond pumps and filters will not only clean the water, but kill algae, encourage beneficial bacteria growth, and create water features. I’ve put together the following information to help you find a good option for your pond:
Different Types of Filtration
Many pond pumps come with filters that include different types of filter media. Filter media simply refers to the substance doing the filtering.
When buying a pump, you can check to see if it’s easy to change the filter media – you may decide that a different media will work better in your pond.
The types of pond media fall into three main categories. Here are some of the different types of filter media, their uses, and why you might want to look out for them:
Mechanical Media
This includes substances such as sponges, filter foams, and filter wool.
The purpose of mechanical media is to clear the large particles from the pond water. Generally, the water will pass through the mechanical media first, before passing through other filters.
Once water has passed through the mechanical filter media it will be visibly cleaner to the human eye – particles of dirt, vegetation, small stones, etc. will all be removed from the water at this stage.
Mechanical media is essential in a filtration system.
Larger particles need to be removed from the water first before other filters can get to work on a deeper level. As a result, mechanical filter media requires the most maintenance – these are the filters that often get clogged up with dirt.
Mechanical filter media will need the most cleaning or replacing. Make sure you have enough of your chosen mechanical media in your house to replace it when necessary.
Chemical Media
Chemical media is not found in all filters. It is often chosen to do a specific job, which you may or may not deem necessary in your pond.
Chemical media includes substances such as Phosphate remover, Carbon, and Zeolite.
Carbon is used to remove odours and impurities, Zeolite to remove ammonia, and Phosphate remover will tackle Phosphate.
Carbon is the most frequently used of the chemical media, and should be used in conjunction with mechanical and biological media. It’s what boosts clear filtered water to the next level: crystal clear sparkling water.
Zeolite shouldn’t be used often, only in times of crisis when there is an emergency relating to ammonia in the water. If it is used too frequently it will have a negative impact on the pond’s ecosystem, effecting the health of plants and pond life.
Phosphate remover will help tackle problems pertaining to high Phosphate levels in the pond. Too much phosphate can cause excessive algae and weed growth. Keeping Phosphate levels down will limit this growth.
Chemical media should be changed monthly at least. Once chemical media has performed its chemical process, it is no longer useful and should be thrown away.
Biological Media
This includes substances such as ceramic shapes, plastic beads, and K1 (Kaldnes Bio-Media).
The main function of the biological media is to trap ‘good bacteria’ and encourage it to prosper in the pond. These bacteria work to maintain water quality, taking waste produced by fish and converting it into substances that are not toxic to them.
Biological media tends to have a lot of rough surface area to trap this beneficial bacteria. When you begin to use it, you may not initially notice any changes. It takes time for the bacteria to grow on the biological media.
Bacteria requires oxygen, so water needs to be constantly running through the filter to keep these good bacteria alive.
You should not rinse your biological media filter because it will get rid of all of the bacteria that has built up. There shouldn’t be a need to clean this media, if the primary mechanical filter is doing its job, the biological media shouldn’t be coming into contact with any large particles of dirt.
Using biological media will really help the health of your fish. Having levels of bacteria that are too low is one of the primary causes of fish death in ponds.
Choosing the Flow Rate
Depending on the size of pond you have and the type of fish you keep, you will need a pump with a different flow rate. Flow rates are written in litres per hour.
If you have a pond with plants and goldfish you need a pump which will circulate at least 50% of the total volume of the pond every hour. In some cases, 75%. So, for example, if your pond is 9000 L, the minimum flow rate that you’ll need is 4500 – 6750 L per hour.
If you have a Koi pond then you need a pump which will circulate 100% of the pond water every hour. A 9000 L Koi pond would require a pump with a minimum flow rate of 9000 L per hour.
To work out the volume of your pond, use the following equation:
Length of pond (m) x Width of pond (m) x Depth of pond x 1000
Understanding Flow Rate With Pressurised Filters
When it comes to pond pumps and filters, you may buy them together as a set, or you may buy a pump and pressurised filter system separately.
If you are buying a pump and pressurised filter system separately, there are a few things you need to know to make sure that they are compatible. If you buy the pump and filter as a set, this should already have been taken care of for you, but it’s good to be aware of.
The maximum flow rate of the filter must be at least the same as the maximum flow rate of the pond pump. The maximum flow rate of the filter can also be more than the maximum flow rate of the pump. That’s fine and won’t cause any problems.
For example, if you’re using a pump for a 9000 L pond with plants and goldfish, you may have selected a pond pump which has a maximum flow rate of 6000 L per hour. Therefore, your filter will need to have a maximum flow rate of at least 6000 L per hour.
Working Out Running Costs
Pond pumps can get expensive to run, so it can help to calculate how much it’s likely to cost. Remember, if you have fish in your pond, you ideally want the pump to be running the whole time.
You’ll need to know the wattage of the pump and how much your energy provider charges you per kWh (kilowatt hour).
You will need to do the following equation:
(Wattage of pond pump x number of hours pump used in one day) / 1000 x kWh rate
Let’s say the pond pump is 11 w, used for 24 hours a day, and the kWh rate is 14p.
(11 x 24) / 1000 x 14 = 3.69p
It would cost you less than 4p a day to run the pump for 24 hours.
Additional Features – Are They Worth Having?
Fountains
Fountains help aerate the water and keep it moving. They also have the added benefit of looking great and adding a relaxing sound to the garden.
If you choose a pond pump with a fountain, make sure that the water flow rate is suitable to the size of your pond.
If you want a larger waterfall, you will need a more powerful pond pump than for a small one. However, you still need to base this on the size of your pond – too big a pump for the pond will move the water too much and could injure fish and pondlife.
UV Light
Pond pumps and filters that include UV light have an added attack against pond algae.
As the water passes through the filter, the UV light shines on the water and kills algae.
This is a great additional feature for filters to have and can keep algae levels in the water under control.
LED Lights
Whether or not you want LED lights comes entirely down to personal preference.
Some pond pump and filter units have LED lights included which mean the pond can be illuminated in the dark.
Not only does these create an atmospheric lit water feature in the garden, they can also help in terms of safety because you know where the pond is at all times.
Submersible Pond Pumps and Non-Submersible Pumps
Submersible pond pumps are exactly what they sound like – they’re placed below the surface of the pond and are generally camouflaged in the pond itself. For most domestic ponds, submersible pond pumps are the easiest pump system to set up and use.
For large ponds, or heavily-stocked fish ponds, non-submersible pond pumps could have some advantages. They work well for very large ponds, over 30,000 litres, and are easy to clean and maintain. Given that the pump is above ground, it’s easy to access. Also, it will not get clogged with debris like a submersible pump.
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