Weald Aquatics | Aquarium & Pond Fish Shop in Kent | The Weald Aquatics Blog - Aquarium equipment


Coolings Green & Pleasant
Main Road, Knockholt, Kent TN14 7LJ

01959 532 963

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A look at my filter - the Eheim professionel4+ 600

Blog post written by Andy | 23 November 2017 | Category: Aquarium equipment

One of the most commonly asked questions we get asked in the shop is “what equipment have you got on your tank at home?” and the area that we think is the most important is the filtration.

Everyone will have a difference of opinion when it comes to equipment on aquariums. We will always advise customers on equipment we have either used in the shop or have on our own setups at home.

I have a Juwel Rio 240 at home with African Cichlids, Synodontis Catfish and some gorgeous L-number Pleco. These fish are big and messy so filtration needs to be good.



For a couple of years I had an AllPondSolutions large external filter bought for me as a birthday present. I had no end of trouble with it. Cleaning was difficult, spare parts very difficult to source and when you read reviews on them it was scary how many leaked.

As my fish were getting bigger, I decided I needed something serous to keep the water clean and more importantly the fish happy.

I spent a lot of time researching filters, looking at the technical specifications, customers reviews and costings. I decided to choose a filter that should last me a lifetime and fit any size aquarium I upgrade to.

I went for an Eheim Professionel4+ 600. It is without doubt the most expensive thing I have put on my aquarium so I was really unsure if all of the good reviews and technical spec could justify the price. But I could not be more happy with it.

It has a total filtering capacity for a fish tank of 600 litres (almost three times what I have) and an output of 1,250 litres an hour. It has four large baskets of biological and mechanical media, a polishing pad and prefilter.

Two baskets are filled with Eheim Mech Pro, ribbed plastic rings designed to strain out the larger particles of waste. Then another two baskets are filled with Eheim Bio Mech and Eheim Substrate Pro, biological media with a huge surface area for optimum biological breakdown of fish waste and organic debris. At the top is a polishing pad and prefilter designed to polish your water for crystal clear results. Once your filter is connected a couple of presses on the large priming button on the top of the unit fills your canister ready to go.

So the filtration side is amazing, and setup is a walk in the park, but without doubt the best feature is how easy it is to clean.

The hoses are disconnected from the top of the unit by the simple flick of a switch and press of a button. Not only does this mean the pipes stay primed (full of water) but it also means that they cannot accidentally come off.  When you disconnect the filter from the pipework, thepipes close so no water leaks onto your floor. For those of you with young children like me you will know what can happen! You can then take the filter away to the sink to be cleaned. Just four clips need lifting and away you go.

Then reconnect the tap, flick your switch and away you go again.

It has a ceramic axle which has been specially designed to run quieter. This filter is like a ninja - you don’t know it’s on!

The final feature, which for my hectic lifestyle is a huge help, is the filters “Extender” function. As I have big, messy fish, the fine pads get clogged quickly. The Extender allows you to control the water flow within the filter to counteract blocked filter media and extend intervals between cleaning. A simple turn of a dial redirects the water around the blocked section so keeping water flow high but maintaining biological filtration.

This really is a fantastic bit of kit and I can say my aquarium has never looked better. Not only will this filter be able to handle a huge fish tank if I ever upgrade, but the build quality is superb and will last for years. Eheim are known for their reliability and longevity. My record is a customer who has had his original filter for over 18 years and it’s still running as well today as the day he bought it.

It’s an old saying but very true in this instance, you get what you pay for!


The Eheim Professional4+ 600 external filter
The Eheim Professional4+ 600 external filter

Using backgrounds to enhance your aquarium

Blog post written by Gary | 26 October 2017 | Category: Aquarium equipment

Having a background fitted to the aquarium, whether it’s a picture on the outside of the aquarium or a 3D resin rock face on the inside, will enhance the look of the aquarium as you will not see a bland wallpaper pattern behind the aquarium or other objects to distract you from the fish.

Picture backgrounds used to be attached to the outside back of the aquarium using either double-sided stickers or sticky tape. This caused a problem over time as water would drip down between the back of the aquarium glass and the background leaving dirty, streaky water marks.

To solve this problem a liquid glue is available which allows the picture background to be attached to the aquarium without bubbles or streaky marks, giving a crystal-clear picture for many years. If you wish to change the background it can be peeled off and a new background fitted.

For a more natural look in the aquarium, a 3D background can be fitted. This will need to be done before the aquarium is filled with water as it is fitted inside the aquarium using a silicone glue which will need 24 hours to set.

3D backgrounds are available to fit most aquariums. These include a number of different types of rock and colour features. In the Juwel range of backgrounds, filter covers are available to blend in with the 3D background disguising the filter box.


Some of the Juwel aquarium backgrounds
Some of the Juwel aquarium backgrounds

Fitting a New Filter to an Aquarium

Blog post written by Gary | 24 June 2016 | Category: Aquarium equipment

If you are going to upgrade your existing internal or external aquarium filter, you will need to avoid losing all the beneficial bacteria in the filter.

To maintain good water quality when changing filters, you will need to run both the new filter and the old filter together for two weeks. This will ensure that the new filter will mature  with beneficial bacteria colonising the new filter media from the old filter. Adding Bacterlife which is a filter starter will also help to boost and maintain the bacteria in the new filter.

Having checked your water quality and made sure that the ammonia and nitrite levels in the aquarium are correct, the old filter can be removed.

Should your filter fail before a new filter has been installed in the aquarium, you can use the media from the old filter and place it in the new filter. If you are replacing the filter with the same make of filter this will not be a problem; however if the new filter is different then you may need to cut the old media to fit the new filter. By using the old media you are still retaining the beneficial bacteria which will help keep the aquarium water in good condition. Again adding Bacterlife to the aquarium water will boost the bacteria in the new filter.

Once the aquarium water quality is correct, then the old media in the new filter can be gradually replaced over a period of weeks.


Eheim filters. On the left is an Eheim external filter and on the right, an internal filter.

A guide to filtration

Blog post written by Gary | 12 March 2014 | Category: Aquarium equipment

Why do I need a filter?

Filters are essential piece of equipment for keeping the aquarium water in excellent condition. Also they remove waste produced by the fish, stopping the water becoming polluted, which in turn could cause the fish to develop diseases or die.

What filter will I need?

The size and type of filter you will require is dependent on the size of the aquarium, what fish you will be keeping and your budget.

How filters work

All filters have an electric pump which moves water through the filter, passing through three stages:
  • Mechanical
  • Chemical
  • Biological

Each stage will use various media to maintain water quality.

Chemical filtration

Using different types of media, either activated carbon or a resin, chemical impurities in the water can be removed effectively. Both media are either supplied loose or in net bags ready for use.

Activated carbon works by adsorption (i.e. chemical molecules attach to the outside of the carbon). This means most carbon media become filled up within a couple of months and will need to be changed to continue removing chemical impurities from the water.

Resin media are used for specific removal of chemicals in aquarium water such as phosphates and nitrates from freshwater aquariums.

There are some resins which last up to 6 months and will remove heavy metals, copper, phosphates and nitrates all in one go.

Mechanical filtration

There are a number of different types of media which trap solid waste from the aquarium water; these are either a ceramic media or sponges which are graded coarse, medium and fine.

A coarse media usually removes the larger particles while a fine or filter floss will remove very fine particles 'polishing' the water and keeping it crystal clear.

Biological filtration

This section of the filter breaks down the metabolic waste products from the fish, ensuring the water is healthy for the fish to live in. This is achieved by the filter media becoming home to friendly aerobic bacteria (Nitrosomanas), which break down the toxic ammonia excreted from the fish into the slightly less toxic nitrite, which is then broken down by another oxygen-loving bacteria (Nitrobacter) into less harmful nitrates. This action is part of a process known as the nitrogen cycle.

The media used in the biological part of the filter usually have a high bulk density allowing optimum colonisation by friendly bacteria for fast decomposition of ammonia and nitrite. However all sponges used in any filter system will be capable of housing friendly bacteria to break down the fish waste.

Types of filters

There are three main types of filtration for the aquarium:
  • Internal
  • External
  • Undergravel

Each type of filter will have some advantages and disadvantages. Choosing the correct filter is essential for keeping your aquarium in the best condition.

Internal filters sit inside the aquarium and are ideal for small to medium aquariums and are easy to maintain and inexpensive to buy.

The downside is that the filter, being inside the aquarium, takes up space and can also look obtrusive. Furthermore, their size can be restrictive when used with large messy fish such as goldfish and cichlids.

External filters are usually sited under the aquarium inside the cabinet.

As external filters are larger than internal filters they have more media inside which results in less frequent cleaning than internal filters and are more versatile with various specialist media available to improve the water quality.

External filters are usually more expensive than internal filters but will be worth paying the extra money for versatility and greater filtering capacity.

Undergravel filters take more time to keep clean and can cause problems with a planted aquarium. They are also not as versatile as an internal or external filter. However they have a larger surface area than internal filters and are ideal for messy fish and are also cheaper than internal and external filters.

Internal filters

The filter is usually fitted to the back of the aquarium just below the waterline for the best results.

Internal filters usually consist of a number of sponges with added biological media in the larger versions to cope with the added biological load which comes with a larger aquarium.

The operation of the filter is simple; water is drawn into the bottom of the filter through the various sponges which trap debris from the aquarium water. At the same time, friendly bacteria will colonise these sponges breaking down any toxic waste in the water.

Water is then pumped out into the aquarium via a variable nozzle from which the flow of water can be adjusted and directed; at this point air can be injected into the flow of water by means of a venturi system.

External filters

External filters usually fit into the cabinet under the aquarium connected by two tubes. Water is removed from one end of the aquarium, cleaned and then returned back to the other end of the aquarium via a spray bar or other spray nozzles.

Cleaning the water in an external filter is achieved through various sections. The first is the coarse mechanical cleaning which removes the larger particles, the second is biological which cleans the water of toxins and the third is the polishing which removes the very fine particles. Finally there is the chemical filtration, which takes out all chemical impurities from the water.

As the external filter has a large filtering capacity, the various sections of the filter can be adjusted to suit the tank conditions, for example, a larger coarse section for large messy fish like goldfish or specialist media to greatly improve your water condition.

Many of the new external filters now have a self-priming mechanism which allows water to be drawn from the aquarium into the filter ready to be pumped back into the aquarium. This device makes life easier when cleaning or servicing the filter.

Undergravel filters

An undergravel filter is normally a plastic tray that has a space underneath with gravel on top which is fitted to the bottom of the aquarium. One or more uplift tubes are fitted to the plastic tray through which water is drawn, either by a water pump (known as a powerhead) or an airstone powered by an airpump. The action of the water being drawn through the uplift tube pulls the water through the gravel which removes particles and toxins keeping the water clean.

Servicing filters

Most internal filter sponges will need to be cleaned every two to four weeks depending on stock levels and the type of fish kept in the aquarium. When cleaning the sponges from an internal filter, they should be rinsed in water that has been taken from the aquarium. Doing this will retain the friendly bacteria in the sponge. If the sponges are washed in tap water the chlorine in the water will kill off the friendly bacteria and this will lead to a rise in the potentially toxic ammonia and nitrite, which in turn could cause the fish to develop diseases or die.
External filters will probably need less cleaning as they have a larger volume than internal filters, so will be able to collect more debris over a longer period.

Impellers which are fitted to all pumps both external and internal will need to be cleaned regularly. Refer to the manufacturer's instructions on how to do this.

For external filters, the feed and return pipes will need to be cleaned. This can be done with various sized flexible pipe brushes.

Maturing a filter

When a new filter is added to an aquarium, as previously pointed out the friendly bacteria have not colonised the filter.

If the filter is to replace an already working filter, the best solution is to run both filters together for about two weeks before removing the old filter, as this will allow the new filter to mature quicker and also keep the water in excellent condition.

If the filter is in a new tank without fish, it can be matured either by using a maturing liquid or using hardy fish such as Zebra Danios.

LEDs: The new lighting for aquariums

Blog post written by Gary | 14 November 2013 | Category: Aquarium equipment

LED lighting technology has improved over the last couple of years, opening up a whole new concept in aquarium lighting for both marine and freshwater fish.

LED lighting has many benefits. Under normal use they should not need replacing for years. Also LED lighting operates at a lower temperature, therefore the aquarium will not overheat, and finally the cost of running LED lighting is significantly lower as LEDs do not consume a great amount of power. This is in contrast with metal halide lights and fluorescent lighting which can be expensive to run and can affect the temperature of the aquarium water.

Controlling LED lighting for marine and freshwater aquariums is now much easier due to the range of LEDs available and their low power consumption. Creating sunset, sunrise, daylight and moonlight phases are all possible using a real-time clock for accurate timing. Dawn to dusk and storm force simulations can encourage breeding in certain species and also help control nuisance algae in the aquarium by controlling photo periods.

Over the coming months we will be increasing our range of LED lighting to include luminaires, moonlight effect LEDs and marine lighting.


A couple of examples of LED aquarium lighting
A couple of examples of LED aquarium lighting


A couple of examples of LED aquarium lighting.

Eheim Ecco Filter Cleaning

Blog post written by Gary | 04 July 2013 | Category: Aquarium equipment

Our latest pictorial guide below takes you through the whole process of cleaning the Eheim Ecco filter. The cleaning description refers to the Eheim Ecco pro200. The same cleaning schedule can be used on the Ecco pro130 and Ecco pro300. Previous models of the Eheim Ecco filter system can also be cleaned using the same cleaning schedule. The only change on the older models is that the coarse prefilter sponge is not fitted.

We have the complete range of spares available for all the Ecco range of filters at Weald Aquatics.


Turn off the Ecco filter at mains switch, turn off both taps and disconnect taps from filter.
Remove the filter from the aquarium and move handle from upright position to its lower setting. This action raises the filter head unit away from the filter canister.


Removing the head unit allows access to the main media canister.


Remove coarse pre filter sponge and clean (the sponge can be cleaned under tap water), and replace if in poor condition.


Remove main media canister and separate containers to gain access to the media. The top white fine filter should be changed or cleaned every time the filter is cleaned. The biomedia and coarse filtration media should be cleaned in a bucket of aquarium water to retain the friendly bacteria. Reassemble when cleaned and place back into filter canister.



To clean the impellor assembly, squeeze lugs together and pull away from head unit. Remove impellor assembly and clean, being careful not to lose the two rubber bushes on the ceramic shaft. Clean impellor shaft and impellor chamber and again be careful because the ceramic shaft can easily be broken.


Remove auto siphon cage and ball, clean and check ball is not pitted or worn away. Replace if in a poor condition as this will affect the working of the automatic siphon system.
Reassemble auto siphon cage and ball (the cage can only fit in one direction), reassemble impellor assembly and place head unit back onto the filter canister. Reconnect taps (making sure the taps are on the correct way), turn on taps and push handle back into its vertical position. This action draws in water from the aquarium, filling the filter with water. Wait until the Ecco filter is full of water then switch on filter at the mains. The filter will now be pumping water into the aquarium.

In focus - external aquarium filters

Blog post written by Andy | 10 January 2013 | Category: Aquarium equipment

The ultimate goal when keeping an aquarium is that it's clean, looks good and the fish are healthy. Probably the most important piece of equipment in your set up to achieve this is your filter, and in my opinion the best types of filters are external.
External filters are just that - filters which sit outside of your aquarium, draw in dirty water from your tank through an inlet pipe, pump it through lots of types of media and pump the cleaned water back via a spray bar or outlet nozzle. These filters work on the same principles as internal filters but on a much larger scale.

Instead of having a couple of sponges to do your biological and mechanical filtration, external filters have larger capacities to hold more media to keep large or heavily stocked aquariums visibly and chemically clean. You're going from a unit that holds a few sponges to in effect a 'bucketful' of different types of media in individual compartments. You can also tailor the types of media in your filter depending on your set up. Some fish like soft water so you can add a softening pillow to one basket. If you have large messy fish you can add more mechanical media. Got nitrite problems? Then you can add more biological media. They are incredibly versatile to suit almost any problem. Being that much larger also means less maintenance as they don't need cleaning as frequently, a massive bonus for all you busy fishkeepers out there!

Another great advantage is that the main unit sits outside the aquarium so you don't lose swimming space and your equipment is hidden. Having an external filter also allows you to add other pieces of equipment onto a system using the pumping power of the filter. UV sterilisers, in-line heaters and surface skimmers can all be fitted to run in-line with the filter for optimum water quality.

External filters come in all shapes and sizes to suit any set up and budget. Smaller units filter aquariums of 20 litres up to our larger units which can filter tanks of up to 600 litres (I have one of those.... amazing!!).

We have a wide range available in the shop which we will happily run through with you. We are in fact currently running two external filters on our big show tank so you can see them in action!


This is the new Nexx filter. We have one of these as well as an Ecco Pro 200 running on our big cichlid show tank.
The Ecco Pro 300 is an external aquarium filter suitable for aquariums up to 300 litres.