Pond Filtration

Pond Filtration

Pond filtration has come a long way since sponges stuck on the front of your pond pump. Cascade has always sold filtration systems suitable for the size of the pond and its stocking level of koi and pond fish. There are many shapes and sizes of filters available today but not all work as well as you would expect. There is a distinct difference in filtration for a pond with koi in and filtration for a koi pond.

This section on Pond Fitration is designed to help you with the basics of filters for small to medium ponds up to 1000gallons/4500Ltrs, probably with a mix of pond fish and plants. Please refer to Koi Filtration for larger pond and koi filters.

Laguna Clearflo 5000 Kit Laguna PressureFlo 5000 Eazy Pod filter
Ecoclear Filter kit Laguna PressureFlo 2500 Laguna Clearflo 8000 Kit
Laguna ClearFlo 2500 Kit Filter start Laguna Master Test Kit
Pond Filtration Pressure Flo Diagram



Who says cleaning your pond filter has to be such a long messy job?

The unique, patented backwash system enables you to perform routine cleaning in seconds, without opening the canister and the handy clogging indicator even tells you when cleaning is required.

The performance isn't too shabby either, with powerful mechanical, biological and ultra violet filtration working in unison to guarantee clean, healthy water. All you need do is sit back and enjoy a beautifully clear pond.

Clearflo 2500 - Pond filter & pump kit - OUR PRICE
Clearflo 5000 - Pond filter & pump kit - OUR PRICE
Clearflo 8000 - Pond filter & pump kit - OUR PRICE
Clearflo 12000 - Pond filter & pump kit - OUR PRICE

Evolution Aqua Koi & Pond Filter Eazy Pod

A Lower priced smaller version of the Nexus Eazy the worlds number one proffessional koi filtration system. The Eazy Pod complete mechanical and biological filter system for garden ponds up to 20000 litres or koi ponds up to 10000 litres.

Eazy Pod
  • The Eazy Pod is a complete filter system for smaller ponds with unparalleled results
  • The Eazy Pod has a small footprint and stands only 23 inches tall
  • The Eazy Pod utilises proven Eazy 200 & Kaldnes technology
  • The Eazy Pod gives incredibly clear water
  • The Eazy Pod has a Quick and eazy cleaning cycle with no wet or dirty hands
  • The Eazy pod can be used as a complete filter on a quarantine system
  • The Eazy pod can be used as a pre-filter at the front of any new or existing system
  • The Eazy pod can be used as a polisher at the end of any system
  • The Eazy pod can be used off a mid water feed to aid mechanical filtration
  • The Eazy pod can be used on a skimmer line as a mechanical filter
Evolution Aqua Eazy Pod – Complete filter system - OUR PRICE

The Filter is an essential part of the pond set-up, as it removes solid waste and ammonia, nitrite from the water. Without it, there is no efficient and reliable way of maintaining the water quality in your pond. It is therefore unkind to keep fish in a pond without adequate filtration. It is important, therefore, to have an understanding of how a filter does its job, and how to look after it. All the koi and pond filters from Cascade are designed to remove ammonia, solid waste, as well as odours, colourants and pollutants from the water.

Filters remove ammonia biologically, utilising naturally occurring nitrifying bacteria. These bacteria convert ammonia into nitrite, and then they turn nitrite into harmless nitrate. Once the filter is up and running properly, it will permanently keep ammonia and nitrite levels at virtually zero.

Starting Your Filter
Before the filter can efficiently remove ammonia and nitrite from the pond water, it must first become fully colonised with nitrifying bacteria. This can take some time and is a process known as filter “maturation”. Each time a fish is put in the pond it will add to the total amount of ammonia being produced.The ammonia level will therefore increase slightly. Because there is more ammonia for the bacteria to utilise, they start to multiply until there are enough to use all of the ammonia being produced. The ammonia level will then fall back to zero. As the ammonia level falls, the amount of nitrite produced by the bacteria will start to increase. Therefore, the level of nitrite in the pond will rise. The increasing nitrite level means that the bacteria that break it down can start to multiply until, as with the ammonia, there are enough to use up all the nitrite that is being produced. The nitrite level can then fall to zero. As this occurs, the nitrate level increases.

In order to avoid dangerous peaks in ammonia and nitrite levels, the pond should be stocked slowly, allowing the filter to “catch up” with each new addition of fish.Adding a bacterial filter booster can boost the maturation process. As a general rule, a few fish should be added every one to two weeks. Once the pond is fully stocked, the ammonia and nitrite levels should remain permanently at zero. It can be very useful to have a couple of test kits during the initial stages of getting the filter going. Cascade sell test kits for testing levels of ammonia and nitrite, which are easy and quick to use. By testing, you will know if the ammonia or nitrite is getting to dangerous levels, and be able to take remedial action before any damage is done. The best way to decrease levels is to dilute them by doing a partial water change, using tap water conditioned with a dechlorinator.

Pond Filtration

Ultraviolet Clarifiers
Ultraviolet clarifiers are designed to prevent green water forming in the pond. They work by killing the algae responsible for green water, allowing it to clump together so that it can be sieved out by the filter. Once in operation, they will keep the pond clear, so that you can observe your fish easily and enjoy your pond more. They also prevent imbalances in water quality that can be caused by green water. Cascade has ultraviolet clarifiers that have been designed to efficiently remove green water from the pond, and stop it reoccurring. They are available in a range of sizes and work very well in conjunction with all Cascade pond filters. Many pond filters come with built in U.v clarifiers so when looking for pond filtration, select a filter with a large wattage U.v.

Green Water A widespread problem encountered by koi keepers is green water. A suspension of microscopic algae will bloom under specific favourable conditions, causing the appearance of the pond to deteriorate into a pea green soup in only a couple of days.

Green water can be one of the simplest pond problems to cure. UV clarifiers are safe, cheap to run and easy to install and are a guaranteed way of preventing algae from causing unsightly green water. Microscopic algae cells that before were too small for a filter to remove, now clump together when exposed to the UV light into particles that can be removed by a conventional filter. UVCs are so successful at their job that no pond should be without one.

How the UV system works
A UVC should be installed so that it is pump-fed, positioned either between a submersible pump and a filter or after a dedicated UV pump and the return to the pond. This will ensure full bulb coverage improving the efficiency of the unit.

The UV lamp is sealed away form the water within a clear quarts sleeve. As water is pumped through the unit, the UV light causes the exposed algae cells to clump together, resulting in crystal clear water.

A UV clarifier should run continuously to have the desired effect with the UV out put of the bulb largely determined by the power consumption of the bulb (described in Watts). Units start at 4W for the smallest ponds, right up to 55W bulbs which are rated to clear a 10,000 gallon pond. For larger volume ponds, multiple UV's can be installed to cater for the UV output required to guarantee clear water. As the power consumption of UVCs from even the largest of koi ponds are less than that of a household bulb, there is no need to be concerned with a UVCs running costs. It is difficult to list any serious disadvantages of using a UVC and as a result, they can be installed to carry out their clearing role with great confidence. It is not possible to overdose with UV and its action is limited to the water which passes beneath the bulb. Consequently a UVC is very environmentally friendly and will not interfere with other desirable plant growth in a pond.

Perhaps the most widely acknowledged problem with using a UVC is that blanketweed can get out of control in a crystal clear pond. Spoiled with excellent growing conditions and a ready supply of nutrients no longer utilised by green water, blanket weed growth can prove to be quite phenomenal. This can be controlled by using phosphate removing additives that will starve blanketweed of its necessary nutrients.

A UVC should be turned on in the spring, having been fitted with a new bulb (which will last for 12 months), and maintenance on a UV unit through the season is minimal.

The quartz sleeve may need cleaning to remove sludge or mulm and in extreme cases, may need replacing if it has accumulated a coating of stubborn lime scale. Most UVCs are sold with universal tapered hose connectors which will fit most hose diameters, which are fixed in place with jubilee clips.

Getting the most from your UVC
In order to keep your UVC working efficiently the bulb should be replaced approximately every 8000 hours (around once a year).The best time to do this is in early spring/late winter, Cascade suggest Easter weekend before the algae starts to grow again after the winter. The quartz sleeve should also be kept clean using a soft cloth, as a build up of limescale will cut down the amount of light that hits the water. Sizing your unit carefully is very important, as the effectiveness of the ultraviolet light is dependent on its contact time with the water.

Installing the correct equipment from the start will ensure that your pond provides an environment which will keep your pond fish healthy and happy.

Laguna Clearflo 5000 Kit Laguna PressureFlo 5000 Eazy Pod filter
Ecoclear Filter kit Laguna PressureFlo 2500 Laguna Clearflo 8000 Kit
Laguna ClearFlo 2500 Kit Filter start Laguna Master Test Kit

Koi For Sale

Cascade select Japanese Koi and Israeli Koi every year. Cascade only select the very best koi. Koi health, Koi quality are paramount. All koi are acclimatised and only sold when the koi are ready. Try our koi varieties & koi for sale sections.


Blanketweed is the curse of most koi and pond keepers.Click here for some great blanket weed products, Evolution Aqua has blanketweed inhibitor, try Goodbye blanketweed or Viresco Koi or maybe Blagdon Blanketweed control unit.

Pond Liners

The most common method of koi and pond construction is with a butyl pond liner.
Cascade sell Butyl pond liner, Pvc pond liner. Online Shopping at KoiBitz gets the best Butyl and Pvc pond liner prices in the UK.

Pond Pumps

Cascade offer a vast selection of Pond pumps for watergardening, waterfalls, filtration
Call into one of our branches for Expert advice on all aspects of pond pumps and filtration. We stock pond pumps from Laguna, Hozelock, Oase, Blagdon.

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