Mud Bed Aquarium Filtration

Mud bed filtration is similar to that of other sand based aquarium filtration systems, however the substrate is made of such a small grain size that it is very much like mud. A good filtration method to equate a mud bed to is the refugium.

In the refugium filtration method various types of macro algae are grown in the fine sand. The mud bed filtration system is effectively the same, however instead of sand mud is used instead. It is not just normal mud though, it is a mud which is full of various elements and minerals. These elements and minerals are slowly released from the mud into the water column.

A mud bed system is normally run in an aquarium or some other container located under the main display aquarium. Some aspect of mechanical filtration is required to remove any large particles from entering into the mud filtration area. This can be performed at the end of the overflow(s) by passing the water through very small chunks of live rock etc. After the water has been through the mechanical filtration it enters the mud filtration aquarium. The macro algae consume nutrients from the water and various elements are slowly released into the water from the mud bed. The water then normally passes through some type of grid or through another chamber full of small pieces of live rock the purpose of which is to prevent any of the macro algae from leaving the mud area and blocking the return pump. Once the water has passed into the pump area it is returned to the display aquarium.

In a mud based system the lights are normally left on for 24 hours a day. This allows the macro algae to photosynthesise and grow. It is only when macro algae grow that they consume nutrients from the water. It is best to use lighting which is designed for the growth of plant life. A couple of fluorescent tubes will suffice, ensure as said that they are for plant life and have a Kelvin rating of around 6000. Lights with this Kelvin rating have more colour in the yellow/red area which benefits the plants.

A normal rule of thumb for a mud based filtration system is to pass in the region of 10 times the total water volume per hour. This needs to be considered when designing the aquarium system as the total amount of water in the system will determine both the overflow size and the size of return pump required.

As with a refugium there may be a requirement to harvest the macro algae if it becomes too dense. Never pull the algae out by the roots - instead cut the plants back with an old pair of scissors or similar. Harvesting the algae will allow more light to penetrate into the areas where the algae grows. One point to remember is that you should not add this macro algae back into the aquarium as you may reintroduce the nutrients back into the water.

A mud based system combined with macro algae removes a lot of the nutrients (nitrate, phosphate etc) and dissolved organic compounds as well as replenishing trace elements.

A lot of aquarists who utilise a mud based system for filtration do not run a protein skimmer. It is not recommended to do so by these aquarists because of the amount of particulate matter which is extracted from the water by protein skimmers. When viewing a mud based system you can actually see the fine particulate matter in the water. The water is still clear, however it is full of fine matter which some life in the aquarium can use for energy.

Of course there are also aquarists who do choose to run a skimmer, however the majority of these run the skimmer part-time (i.e. throughout the night, turned on/off via the use of a timer). The majority of these aquarists decide to run a skimmer as they are very wary of turning it off. I have run a system using a mud based method combined with live rock for many years without problems. The only thing you need to ensure when you run a system like this is that detritus is removed from the main display aquarium regularly and that weekly water changes are performed. A lot of aquarists who do not run a skimmer on their mud based systems do not have a sand bed in the display aquarium due to the build up of detritus which can occur. Instead they go ‘bare bottom’ in the aquarium. The glass which is visible at the bottom of the aquarium quickly becomes covered in coralline algae as well as other types of life so looks more natural as time passes.

The aquarists who decide not to run a skimmer have reported a higher level of particulate matter visible in the aquarium water which the corals, and other filter feeders consume. Because of the amount of particulate matter in the water column you should see good polyp extension from your corals as well as hopefully having success in keeping some of the harder to keep corals. Obviously you cannot just expect to be able to keep these more difficult corals just because you are running a mud based system - you must still ensure that you have optimal water parameters and that the requirements for the livestock in question are met.

Implementing a mud based filtration system is fairly straightforward. It is best to have an aquarium which is split into three or four sections. This can be accomplished yourself using glass and baffles or you can have one made for you at your local fish shop.

The first area is where the live rock is placed and is where the water from the display aquarium, via the overflow(s), enters the filtration aquarium. The purpose of this section is to remove any large detritus from the water as well as break up any air bubbles. Using live rock in this area is a good idea rather than another type of media as it is a natural filtration medium and will actively help in filtering the water rather than hindering it as other types of media could do.

The second section is where the mud is placed as well as the macro algae (caulerpa etc). The mud is poured into this section and the macro algae planted within it. To give the macro algae a chance to put its roots down trap it gently under a piece of live rock. Once the macro algae takes hold the piece of live rock can be removed. It is advisable to add a few varieties of macro algae as some may not take root. Caulerpa is one species which does tend to do well and there are numerous varieties available. Because of the amount of water flow which can be created in the central chamber some people choose to create small containers 1 inch or so high and 1-2 inches apart in the bottom of the chamber. This prevents the mud from moving around and building up in a pile at one end of the chamber.

The third or fourth section is where the return pump is located and is protected from the second central section via a baffle of some type or even more chunks of live rock contained in a chamber. If you are running this mud aquarium as your sump then your heaters for example can also go in this area.

A couple of fluorescent tubes will suffice for the lighting above the mud section and should remain on for 24 hours per day. As said attempt to use tubes which are designed for plant life as this will help the macro algae grow.

Because of the mud releasing essential elements into the water the mud bed will eventually expire, therefore it is recommended that half of the mud bed is replaced about every two years however I would recommend that you rely upon the manufacturers recommendations in this area.

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Tags: Aquarium Filtration, Care, deep-sand-bed, Equipment, plenum, Water Quality

The Canister Filter - A Thing Of The Past Or Still Useful?

Technology marches on and there are quite a few devices that are available for use with a marine system. The canister filter is not new and has been with us for a considerable period.

Canister filters are made by quite a few manufacturers. They are usually shaped, err, like a canister, though there are models available that are square. As time has passed they have become very reliable.

A canister filter could be considered a closed circuit. Seawater is delivered to the unit down a flexible tube, passes through the canister media and is then returned to the aquarium through another flexible tube powered by a built-in pump. It is best if the intake and outlet are at opposite ends of the aquarium, though perhaps this is not so important nowadays when the high flow rates within the aquarium are considered. Nevertheless, it is best to keep the intake and outlet apart.

What can the canister be used for? Biological filtration is the first use that comes to mind. Though filtration this way has been superseded by live rock an aquarium can still be successful using a canister, and many aquarists still do. The cost of live rock is high, and so canisters find a use. They need to be filled with a good bio-media, and this media needs to be protected by efficient mechanical filtration, such as sponges and filter wool. The cleaner the bio-media is kept, that is, kept clear of sediment, the better. The canister needs to be sized to the size of the aquarium, and the manufacturer’s specifications will include recommendations. One point about these recommendations - the flow rate advised by some manufacturers is often with the canister empty, when it is filled with media it will be less. Consideration can be given to using two smaller canisters so there is a backup. The canisters can be serviced alternately.

Cleaning the mechanical media in the bio-filter is important otherwise the seawater flow will decrease. It is a good idea to clean this media after two weeks. It may be that it remains reasonably clean in which case increase the period to three weeks and so forth. Sometimes it is recommended that the filter should be cleaned when there is a noticeable reduction in the flow rate. This is not really acceptable because for this to happen the media will be very dirty. By cleaning and checking the condition of the mechanical media the aquarist can arrive at a reasonable service period. A watch should always be kept on flow rates even with more regular cleaning because of the importance of bio-filtration - a failure or reduction could result in serious consequences. In addition, the bio-media itself must never be washed in tap water as this will kill the bacteria. If cleaning is essential then seawater should be used, and this can be at a routine change using the old seawater. The media should be very gently stirred with the fingers under the seawater to remove dust and debris. It will never look ‘as new’ but this doesn’t matter.

If the filter is used for bio purposes then the seawater leaving the filter will be low in oxygen. This is because the bacteria that carry out the bio-filtration function are oxygen hungry. The oxygen can easily be replenished by releasing the returning seawater at the surface.

There is an important point with bio-filtration in a canister filter. This is that the ‘Nitrogen Cycle’ will arrive at nitrate and stop. The ‘Nitrogen Cycle’ is the process where bacteria convert ammonia to nitrite, then the nitrite to nitrate. A watch should be kept on nitrate levels, though this should be done in any marine system anyway.

If other means of bio-filtration are in use then the canister is not redundant. It can be used for purely mechanical purposes, that is trapping detritus that is in the seawater. In this case only mechanical filtration such as sponge and filter wool are in use, and these can be washed under the tap. If they are showing any deterioration they should be replaced. This of course also applies to the mechanical filtration within the bio-filter.

The canister can also be used for activated carbon and/or anti-phosphate media. These are put in after the mechanical filtration. Certain anti-phosphate media types with a very fine particle size are usually better in a fluidized reactor, as in a canister they could tend to clog. Cleaning the mechanical filtration area is the same as above, and a note should be made of when the activated carbon and/or anti-phosphate media are due for renewal.

There is another use for the canister. If a small canister set up as a bio-filter is kept running on the display aquarium, or better the sump as connection is easier and the intakes/outlets will not be seen, then a permanently ready bio-filtration unit will be at hand. This is useful for those aquarists who have wisely used a small aquarium for quarantine purposes. This could be required again for quarantine of a new arrival, or as a hospital area for a fish with a problem. There isn’t a need to keep this aquarium full of seawater, but if required it can be filled and the bio-filter is ready.

So the canister filter is not out of date. Modern types are very reliable and much easier to service than the older models, which could be fiddly. Having a canister in the system could certainly be useful.

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Tags: Aquarium Filter, Aquarium Filtration, deep-sand-bed, Equipment, live-rock, plenum

Aquarium Filter Media - Is There Such A Thing As The Best One

The function of the filtration is to ensure that the relevant nutrients in the water are processed. These nutrients occur due to the inhabitants being kept in a closed environment - the aquarium.

Of course life in the ocean also creates waste yet the ocean is so vast that the waste/nutrients are controlled. Look at the oceans filtration - huge sumps, loads of live rock, the biggest deep sand beds ever, mangrove swamps etc.

In our aquariums fish and food are the biggest problems. As soon as you add fish to the aquarium there is a requirement for you to feed it. The trouble is the majority of aquarists unfortunately overfeed. Not on purpose I hasten to add feeding is a pleasurable time and as aquarists we all want to ensure that our fish are well fed.

Fish being fish though will just eat. This is a natural response and is primarily because they do not know when their next meal will come, therefore the gorge.

This causes the problem. There is a lot of food which does not get eaten and starts to decay, other food is passed through the fish’s digestive system either un-digested or partially digested as they ate to much, normal faeces plus urine.

Unless this waste is broken down and processed by the aquariums filtration system then before long the fish will be living in a nutrient loaded soup.

Not nice as I am sure you will agree.

This is why it is so important that a good filtration system is implemented. There are various types of filtration which can be utilised in the aquarium some of which are listed below:

• Canister Filter
• Internal Filter
• Fluidised Filter
• Plenum
• Deep Sand Bed
• Live Rock

In the above examples there are some of these which require filter media. Filter media can be many things - sponge, ceramic rings, plastic balls etc, however it can also be sand or even rock. For example the filter media used in a deep sand bed is the sand itself and the filter media used in live rock is rock.

There are a lot of people who see filter media as being something which is man-made which is added to the aquarium. It is of my opinion that filter media is anything where the required bacteria can function.

Any type of filter media can and will work. The issue is not about where the bacteria live it is how the filtration itself is maintained and how efficient the filtration is.

A good example of this is a sponge filter media. When the filter media is working efficiently the sponge will be clean and not clogged in any way, however over time the sponge if not maintained correctly will become clogged and the efficiency of the filtration will decline.

Another example would be live rock. If the live rock is not kept clean by either manual methods or by the introduction of a natural clean up crew then the filtration may not work at a level of efficiency which is could do if it was clean.

I do admit that there are some filtration media which does allow for more nutrients to be converted. The majority of filtration media finishes at the creation of nitrate. A deep sand bed, live rock or the two combined when maintained correctly will allow for the processing of nitrate as well.

Maybe the article should have been titled ‘Aquarium Filter Media - Which is The Most Efficient’ as it is of my opinion that there is no such thing as the best filter media…just the most efficient.

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Tags: Aquarium Filter, Aquarium Filtration, Aquarium Maintenance, Care, deep-sand-bed, filter media, live-rock, plenum

Why Does Sand Become Such A Detritus Trap?

Not all marine aquarium systems use sand. These are said to be ‘bare-bottom‘, and the aquarists have decided to forego a sand bed in the interests of cleanliness. When the aquarium is new, the bare bottom does look unfinished, but in a little time if the seawater conditions are correct the bottom is covered in different algae, and this can look very attractive. Note this is not the often persistent nuisance algae, but decorative types.

I would hazard a guess that the majority of systems have sand in. This can be either decorative sand or a deep sand bed (DSB) or plenum (a raised DSB).

The sand used on a DSB is of fine particles, and dirt that reaches its surface has a tendency to sit there. Eventually it is utilised by the tiny life forms that inhabit the area. Some may penetrate a little way but not a lot and not very far. These beds are around 4″ deep or more.

If the sand is used for decorative purposes only it is placed in the display aquarium and covers the base. The sand is usually coarse and makes a very attractive addition to the aquarium. These beds are often up to 1″ deep.

The reason the sand becomes dirty is mainly because of the size of the grains. In the DSB as stated it is fine, perhaps it could be described as very fine. If a fairly strong water current hits it  a cloud can be raised. Though problems can arise with a DSB, with proper construction and sufficient life it is not usually dirt penetration.

The coarse sand of the decorative sand bed is a different story. Fish faeces, bits of food, dead algae and other general rubbish can fall to the bed. It breaks down and falls between the grains. The grains are coarse enough to allow tiny dirt particles to follow the ’channels’ formed by the spaces between grains. Enough of this dirt can cause the sand to become clogged. This was a major problem with the under gravel filter of yesteryear, which pulled water down through coarse sand and the dirt with it.

With a decorative bed the way to prevent this is to stir the sand frequently with a clean stick. The stirring can be reasonably vigorous and is best done at the time a routine water change is performed. This allows the aquarist to stir the sand and follow the stirring stick with the intake of the water hose, removing dirt. There isn’t any need to do all the sand bed at once, just a proportion at each change. The aquarist can become very expert at this job.

A DSB should never be stirred or the disturbance can spoil the filtration capability of the bed. As said, a well made DSB will possibly look scruffy but should never become really dirty.

It is important to stir a decorative sand bed routinely as described as it prevents the bed from becoming really dirty, which would make the cleaning job much more difficult. If the bed is really very dirty, it would probably be best to siphon out a proportion of the bed at each water change, thoroughly rinse it, and then return it. Routine stirring will prevent the need for drastic cleaning and maintain the attractive appearance of the display aquarium.

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Tags: Aquarium Filtration, Aquarium Maintenance, Care, deep-sand-bed, plenum