What Is Natural Aquarium Filtration

There is one thing that I have learnt in all my years of keeping aquariums – do not underestimate nature!

It still amazes me today how powerful natural aquarium filtration actually is and how many ways there are to actually filter an aquarium or provide additional nutrient export by using the power of mother nature.

Nowadays whenever I am asked for my recommendation as to the best way to filter a marine aquarium I always mention natural filtration. In my opinion and this is purely my opinion live rock mixed with a remote deep sand bed has to be the ultimate natural based filtration available at this moment in time.

The prime advantage of using natural based filtration methods is its efficiency and the advantages that it gives to the aquarist.

A lot of people however have never heard of natural filtration never mind actually understand what it is.

So what is natural filtration?

Any filtration technique applied to an aquarium actually does have an element of nature in it – the bacteria however in a lot of occasions the container upon/in which the bacteria lives is not natural – it is manmade.

A good example of the above would be a canister filter. The bacteria is natural, however the holding device if you will has been manufactured.

Therefore a good way to explain natural filtration is that it is where the bacteria live in any area which has not been manufactured by man.

This is not a set rule however as there are exceptions to natural filtration. One of which would be using macro algae as a nutrient export tool.

Numerous natural filtration methods can be employed in the home aquarium. Some can be implemented for use as a primary filtration method whilst others can be utilised as an additional nutrient export tool.

As already stated natural filtration can be and is an exceptionally powerful tool. Think about the ocean – it is huge, however the natural filtration devices which are in use in the ocean are very similar to what we can use.

The rock structures on the coral reefs are similar to live rock filtration, grass beds are similar to a refugium/macro algae, mangrove swamps are a much larger scale of mangrove usage in the aquarium etc.

Can you see how powerful this type of filtration can be. The ocean has been filtered this way for millions of years and it can and does work in the aquarium.
Although our aquarium are minute compared to the size of the worlds oceans the end result is the same – excellent water parameters.

There is a point which needs to be made however, the filtration has been termed as natural filtration simply because it is similar to what is used in nature or is the same as is used in nature but on a much smaller scale but there will always be an element of human involvement.

That’s right – the care and maintenance. As with all things in this hobby the correct care and maintenance techniques need to be applied and this is no different with natural aquarium filtration. Nature can again be involved in this area for example using hermit crabs, snails etc to keep the rocks/sand clean however there will always be a time where we need to get involved to keep it just right and running at optimum efficiency.

If you are just starting out in this hobby or already have an aquarium and are using man-made filtration then I really recommend that you at least consider natural based aquarium filtration. It is absolutely amazing how powerful it actually is.

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Cryptic Zones – Another Filtration Possibility

There is a scientific term used which is called ‘the gradient concept’. This term basically describes how various marine organisms can be graded according to the amount of light which they receive.

There are two zonal categories which are most commonly used, these are the exposed and the semi exposed zones.

The exposed zone is an environment which is in shallow water and receives a lot of strong sunlight. This is the zone which is typical of the upper reef, otherwise known as a shallow reef. The water currents in this zone are normally quite fast and chaotic, therefore any organisms which live in this area have to be able to withstand such high currents. Due to the high currents there is normally a lot of suspended matter moving around in the water; however with the strong water current a lot of the filter feeding organisms struggle to extract these from the water. This zone is where the majority of the light loving high current SPS corals live and is effectively the environment which we attempt to replicate in the majority of our reef aquariums.

The semi exposed zone is similar to the exposed zone but both the light and water currents are considerably less. Because of the lower water currents filter feeding organisms are able to extract the particulate matter from the water more easily. This zone is similar to that of deeper reef conditions, and is otherwise known as the back reef. In this zone there are still a huge range of photosynthetic organisms which can survive but this zone, because of the lower light conditions, also provides the non photosynthetic organisms with a place to thrive. Again this environment can easily be replicated in our reef aquariums.

In the marine aquatic world there are effectively three more zones which are:

1. Semi Cryptic
2. Cryptic
3. Filter Feeding

The semi cryptic zone is the zone which occurs in the sections of the reef which are either deeper down the face or in naturally occurring overhangs in the reef structures. This zone has a very low light level and can only support photosynthetic organisms which can survive in this type of area.

The cryptic zone is the zone which occurs in the sections of the reef where light if any is far too weak to support any photosynthetic organisms in any way at all, and can only support non photosynthetic organisms. In the natural reef this occurs either within caves or deep into the overhangs of a reef structure.

The filter feeding zone is effectively a combination of the semi cryptic zone and the semi exposed zone. The difference in this mixed zone is that there is little light but very strong water currents, therefore particulate matter in the water can be delivered and consumed via the various filter feeding organisms. This zone is normally where the non photosynthetic soft corals occur.

Understanding the differences between the zones enables you to be able to see what zones you currently have in your aquarium – you will be surprised as to how many you actually have. You will probably find that you have many or even all of these types of zones in parts of your aquarium, however some may be quite small – e.g. small caves in the rock face.

You need to consider these types of zones when setting up a new reef system and also when introducing corals into the aquarium. When purchasing a new coral you need to understand the requirements of the coral and ensure that you have an area of the correct zone available in your aquarium to support it.

In your aquarium you will have various zones in various sizes, however one which is a valuable addition to the aquarium is the implementation of a designated cryptic zone.

A designated cryptic zone can easily be implemented into an existing system by adding a new aquarium into the system, possibly next to the sump, in the sump etc. This aquarium is filled with aquarium water via an overflow from the main aquarium or a tee off from an existing overflow. A small amount of substrate needs to be added. On top of this substrate is placed some pieces of live rock, sponges, sea squirts, non photosynthetic corals etc – effectively any non photosynthetic organism which can survive in a cryptic zone. The aquarium should then be effectively covered up to prevent any light from entering. Dirty water (un-skimmed as DOC’s are a requirement in this area) is fed to this aquarium at a very slow pace and there is minimal water current. This un-skimmed water is best fed into the cryptic zone along the top of the water. What this does is allow the particulate matter in the water to slowly settle down onto the organisms so that it can be consumed. The matter also falls onto the substrate. This allows for the growth of the organisms and therefore more removal of particulate matter from the water. Water from the cryptic zone normally overflows down to the sump so that it can be skimmed therefore for this reason you will need to install the cryptic zone aquarium higher than the sump so that it can overflow. It is also advisable to add some types of cleanup crew into the cryptic zone aquarium so that they can deal with any particulate matter on the substrate, rock work etc.

I have seen various designs of a designated cryptic zone in use. Some have even been combined with deep sand beds/plenums. Occasionally if you open up the covers and have a look you will be amazed at the life which is growing in there and how fast it grows. The thing I like about a cryptic zone is that sponges can quite easily grow. Sponges are a good filtration tool and utilising a cryptic zone will afford you the opportunity to grow some of them.

Of course more than one zone can be implemented whether this is directly in the display aquarium or by using external aquariums.

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Understand The Nitrogen Cycle – Your Livestock Depend On It

Modern reef aquariums try to be as natural as possible. The modern day captive reef would make yesterdays marine aquarists eyes water – they are so beautiful in total and in detail. Fish only systems house fish that would have been impossible to keep not that long ago. This success is because of natural processes and modern technology.

Whatever type of marine aquarium is kept, reef system or fish only system, there is one function that is totally essential. It isn’t a modern natural ‘invention’ either, it applied to those earlier aquarists just as much. The difference is that in the very early days the aquarists didn’t know anything about it. Before my time a pioneer marine aquarist thought he could keep his aquarium clean more easily by using what turned later into the much used under gravel-filter. I believe his name was Straughan. He was amazed about the length of time he was able to keep livestock, and put it down to better cleanliness. Investigations showed that in fact he had stumbled onto the secret of keeping any marine system basically healthy. In a way it was due to better cleanliness.

Livestock in an aquarium continue with their normal life functions. They are fed. Algae can die and rot as can uneaten food. This protein breaks down into a deadly toxin – ammonia. In the presence of not a great amount of ammonia livestock can be badly affected or die. Fish could hang quietly at the water surface, or swim in a very erratic manner, even upside down, or sit on the aquarium bottom leaning against a rock, and breathing could be rapid. This situation is very serious.

Yet in the modern aquarium the problem of toxins hardly arises, except perhaps in the case of a beginner who does not use patience and stocks too rapidly.

The saviours and the servants of the aquarist are bacteria. These bacteria break down toxins and the process is generally known as the nitrogen cycle.

Ammonia is very toxic and is broken down by bacteria called Nitrosomonas. The toxic ammonia is converted to nitrite, which is also toxic and nearly as bad as ammonia. That’s a lot of good! Well, another bacteria then comes into play and converts the nitrite into nitrate. These bacteria are called Nitrobacter. Nitrate can be bad at high levels, but is safe in comparison to ammonia and nitrite. The nitrogen cycle does not stop at this point, but continues when the nitrate is converted to nitrogen gas. The gas escapes from the aquarium and the cycle is complete.

Simple, nature saves the day!

Yes, it does, but there has to be a catch and here it is – the ammonia/nitrite conversion bacteria need a different environment to the nitrate bacteria.

The ammonia/nitrite bacteria require an environment that provides obviously ammonia and nitrite, and in addition they need a good supply of oxygen. This oxygen can only come from the water (except in one instance) so the aquarist has to provide plenty of water circulation to ensure good gas exchange at air/water interfaces such as the surface of the seawater. The home for the oxygen hungry bacteria can be in a canister filter and the like with suitable media. What is the exception mentioned – this is the so-called trickle filter. As the seawater running down is exposed to the air, oxygen is plentiful.

Providing a suitable home for the ammonia and nitrite bacteria is easy. The aquarist needs to ensure that the canister etc filters are properly matured, and this is achieved by using a prepared commercial maturation fluid. Using test kits, once the nitrite has disappeared the filter is initially mature. The instructions with the fluid will give details which are very straightforward. The nitrite showing as cleared means that there is a presence of bacteria which will deal with ammonia and nitrite. When the filter is initially mature, stocking can commence, but with great care and patience, as the filter is still unstable and needs to adjust to the bio load placed upon it.

The problem – here we go again – with canister etc filters is that the complete nitrogen cycle is not achieved. This is because they operate in an oxygen rich environment. Bacteria that deal with nitrate can live in an oxygen rich environment too, but under this circumstance they will not deal with the nitrate. An environment must be created where there is a lack of oxygen, and in this circumstance the bacteria will turn to the nitrate. The bacteria need oxygen, and the only way they can obtain it is to extract it from the nitrate, which breaks the nitrate down.

So there is no reason why a marine system cannot use a canister etc filter. It does mean though that the aquarist must keep a careful watch on nitrate levels as well as other parameters. Routine seawater changes will control nitrate to a degree, as will good husbandry such as a proper feeding discipline. There are other ways to control nitrates which will not be dealt with here.

There is a way of achieving the full nitrogen cycle, and that is to use live rock. This live rock (LR) can be used in fish only and reef aquariums. In the reef aquarium it has the secondary benefit of providing a material with which to construct the reef.

LR works as filtration because it is porous and provides a home for the bacteria. On the surface and inside toward the surface dwell the bacteria that use oxygen and deal with ammonia and nitrite. Deeper inside, where oxygen levels are depleted, dwell the bacteria that can only obtain oxygen from nitrate. Therefore the total nitrogen cycle is achievable. It is important that sufficient live rock of good quality is provided.

Using LR the aquarist still needs to monitor seawater parameters. Nitrate is included in those parameters, as LR has limits the same as anything else. That said, it is a wonderful filtration media.

Whatever type of bio filtration the aquarist uses, the bacteria will not make many demands, and the demands they do make are easily met. Fail to meet those demands, or pass the point where the bacteria do not have the capacity to deal with toxics, and the consequences could be very serious.

Provide suitable media and well oxygenated seawater, have patience with stocking and do not overstock, and nature’s bacteria will work silently and unseen providing life support.

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Addition To My Deep Sand Bed

My soft coral reef has been running in excess of 5½ years. 3½ years ago I decided to add a DSB (deep sand bed).

I know the above periods are correct as I keep a notebook.

The aquarium was running without any problem, the decision to incorporate a DSB was driven by interest. I wanted to see if I could develop a bed that was full of life as described in various articles.

I haven’t the space for a full size DSB, that is one of the size that follows the guideline. It had to go in-tank as well, and fortunately there is a divider in the tank separating the display area from the pump area. The DSB went in the pump area and is very approximately about one twelfth of the base area of the whole aquarium, or perhaps even less. Therefore any effect on the seawater would be minimal (nitrate reduction for example) but, as said, I wanted one out of interest.

It was constructed with fine sand to a depth of just over 4″ (circa 10 cm). I remember that though I had cleaned the sand as best I could, the display looked like it was wreathed in a thick fog for quite a time. After a few hours it cleared without any ill effects.

The DSB sat there looking very clean and tidy for quite a time. Then I obtained a small amount of sand from Peter’s DSB and laid it on the top. This sand was fairly coarse and sits in a very thin layer on top of the fine sand.

The hope for life appeared, and also no doubt some of it took up residence after moving from the display area. The display area when viewed at night with a torch is quite rich with little shrimps, snails and the like.

After about 6 months the surface of the DSB was a small sea of short waving tentacles, which belonged to small life forms trying to find food in their immediate area. In addition there were a lot of tiny shrimps running about – this was at night when viewed with a torch. In addition there were a few creatures, very small about ¼” (circa 6mm), which swam about, their eyeballs being picked out by the torchlight. The looked a little like brine shrimp but they were not.

This went on, with me feeding the DSB once weekly with small frozen fish pieces. When the fish went in the worms popped their heads up quite quickly, recognising that lunch had arrived.

The worms obviously lived in the sand, but I started wondering were the little shrimps etc lived. The DSB is flat – maybe they were in the sand too? Seemed a bit unlikely to me, but I never managed to track anything back to its lair.

I wondered if I could provide a better habitat for the tiny life. Therefore, 6 weeks ago, I placed some rock rubble at one end of the DSB. The rubble was that from the original rock that I had used to construct the reef – inert and very porous.

The rock is very light which is good, it won’t compact the DSB. The rubble pieces are around ½” to ¾” and form a light layer about 6″ wide and 8″ long. The major area of the DSB remains flat sand.

There has been a clear increase in the DSB population. The tiny shrimps have increased the most, and to a lesser extent so have the ’swimming eyeballs.’ Feeding the DSB has not been increased, so it seems that the noted increase in the population is down to the rubble that went in. So that was a success.

I have kept a watchful eye on the condition of the DSB throughout its life, and particularly after the rubble went in – I was watching for signs of compaction, that is, dark areas appearing in the sand below the rubble. There hasn’t been any indication of any problem.

Though the DSB may assist to an extent with seawater quality, there are two things that have occurred: first I have to make sure that when the grid to the pump area is open during maintenance a fish does not gain entry and eat any inhabitants. Second, when my wife is in bed quietly reading, sometimes I can be found sitting on the floor in the dark, face against the aquarium glass with torch in hand.

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I’ve Got Bio-Balls, Will I Be Ok?

No, no, you’ve got the wrong end of the stick! It’s not some horrible problem at all, but to do with aquariums.

Marine aquariums need bio-filtration, and this is provided by bacteria. The bacteria of course need a place to live and to avail oneself of this free service from nature the aquarist must provide them with a suitable home.

The bacteria operate what is called the Nitrogen Cycle, either fully or in part. To operate in part is easy, all that is required is plenty of oxygen plus ammonia and then nitrite. The bacteria will change the ammonia to nitrite, and then the nitrite will be changed to nitrate. Ammonia and nitrite are toxic, and nitrate much less so.

To support livestock it is enough to do only as in the previous paragraph. The toxic ammonia and nitrite are dealt with. Nitrate is left and this should not harm anything at very low levels.

However, the levels will slowly increase beyond the guideline (for a reef system) which is 10ppm (parts per million) or less. One way of reducing the level is with routine seawater changes. These changes are good for other reasons and should be completed, however nitrate could increase in spite of them. Nitrate increases are not desirable as the appearance of nuisance algae may occur.

Nature has a remedy but it cannot occur where there is oxygen present in any normal amount. The bacteria that reduce nitrate need an environment that is very low in oxygen – this forces the bacteria to extract oxygen from the nitrate thus removing it (it converts to gas and escapes the aquarium).

So bio-balls are a good medium for oxygen hungry bacteria, but not for bacteria that deal with nitrate.

If nature is going to assist with nitrate reduction, a denitrator (a so-called nitrate ’reactor’) could be used. Better, live rock can be used. Live rock has surfaces that can be used by oxygen needing bacteria, and well inside are areas for the nitrate bacteria. Live rock with a DSB (deep sand bed) is even better.

So if an aquarist is using bio-balls the answer is yes, it will be all right, except that the bacteria will produce nitrate and that will be the end of nature’s assistance.

If bio-balls are in use in addition to sufficient live rock (and perhaps a DSB) then the bio-balls can be removed, but remove them a few at a time over a period of weeks. This will allow any bio-load that was supported by the balls to be taken up gradually by the other media.

If the bio-balls were the only media, then none must be removed straightaway. Introduce sufficient live rock into the aquarium, wait a week or two, then commence removing the bio-balls a few at a time as already described. It would be of little use introducing, say, a canister filter for bio-filtration as the end product is the same – nitrate.

A good few years ago bio-filtration methods included balls. Times have changed.

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Can Tonga Live Rock Provide Enough Filtration?

Live rock as has been said time and time again is a phenomenal filtration medium. There are various different types of live rock available all of which provide the required filtration to the aquarium if enough is placed into the aquarium.

There is one in particular however that in my opinion is more decorative and ‘standard’ live rock.

Tonga rock

Tonga rock is different to other types of live rock due to the reason that it looks like branches of a tree. It can be an extremely decorative addition to a saltwater aquarium. Due to tonga rock being thinner and not boulder shaped like the majority of other live rock with the obvious exception of plating rock you have the ability to be able to create fantastic water movement around it.

In my opinion tonga rock is fantastic for SPS corals as you can provide a large amount of water movement and if carefully aquascaped can look amazing. This is not to say that you could not have a fish only aquarium or a soft coral aquarium with tonga rock as you would be able to. You would just have to bear in mind that you will need to create caves etc for the fish to hide in as well as creating ledges to place the soft corals on.

But what about the filtration – is tonga rock as good as other live rock.

Tonga rock does have good filtration capabilities however they are not as good as other live rock. This is mainly due to the size of the physical rock. To purchase enough tonga rock to faciliate the filtration requirement would make it very hard to aquascape.

So what do you do?

In my opinion it is quite simple. I personally would use the tonga rock for decorative purposes and then have an in tank deep sand bed as well. The deep sand bed would be the main aspect of the filtration but the tonga rock would do some as well albeit reduced. You do not need to have the deep sand bed in the display aquarium it could be in the sump in the cabinet. You would just need to make sure that the partiton designed for the deep sand bed was large enough.

One of my dream aquariums (we all have them don’t we) is to have a 3 foot cube tank (3*3*3). In this aquarium a deep sand bed would be placed and tonga rock used for decorative purposes as well as some plating rock to provide some hiding places/ledges. Lighting would be provided by metal halides, the water movement would be chaotic and my corals of choice would be SPS with a small amount of fish.

We can but dream can’t we?

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Can You Add A Deep Sand Bed To An Existing Setup?

Every week I like to pop into my local fish shop, even if it is not to purchase something just to have a look about and have a chat with the owner.

Over the years we have built up a bit of a friendship and over a cup of coffee we tend to sort the world out – both aquatic and non aquatic related!

Anyway whilst I am in there other people of course come in and ask various questions, purchase things and I like to keep out of the way whilst this is happening. I normally go and look at the corals and fish with my cup of coffee in hand.

Yesterday whilst I was there I overheard a conversation between a customer and the owner of the store entailing deep sand beds.

It is probably obvious by now that I am a huge fan of deep sand beds.

Basically the customer had heard that you cannot add a deep sand bed to an aquarium system which is already setup and the owner of the store was patiently attempting to explain to him that it was possible to do so.

The conversation did not get heated but to cut a long story short the customer would not take any advice from the store owner (the expert if you will) and left the store. As far as he was concerned this is what he had been told so it must be right!

It must be very hard for owners of shops, not just fish shops but any shop for that matter to deal with situations like these.

We chatted about it afterwards and he said that although it is hard he will not tell anyone incorrect information even if it means losing their business. It is not just about the money he earns but the love for aquatic life which he sells.

To be honest what he was discussing with the customer was correct and I thought that I would cover it here in case any readers of Aquarists Online have been wondering about this as well.

If you are interested in understanding more about deep sand beds then click the link below :

http://www.aquaristsonline.com/blog/aquarium-filtration/the-deep-sand-bed-one-of-the-most-effective-filtration-methods/

The above article covers how a deep sand bed works, the importance of grain size etc etc.

What we will cover in the remainder of this article is the introduction of a deep sand bed into an existing aquarium system.

It is presumed that you have purchased sand which is of the correct particle size.

I would advise that any sand purchased is cleaned thoroughly in saltwater. The saltwater removed from the aquarium when you do a water change would be fine for this use. An even better way than just washing the sand is to leave the sand covered in saltwater for a period of a couple of weeks.

Some aquarists even run a magnet over the surface of the sand just in case there are any metals in there but this is not a definite requirement.

Once the sand has been prepared you are now in a position to be able to add it to your aquarium.

If you have any sand in your aquarium and it is not of the correct granular size then it will need to be removed from the aquarium. Do not discard it though as you can use some of it to ‘seed’ the new sand bed.

If you have any sand in your aquarium and it is the correct size then it can be left in the aquarium, however do not be tempted to add all of your new sand in one go – add it slowly over time. The reason for this is that when you add new sand the life which lives in the existing sand needs to move higher up in the sand bed and if you put to much in at one go then you may kill them.

Due to displacement some water will also need to be removed from the aquarium.

Turn the pumps/powerheads off in the aquarium and slowly add the sand to the bottom of the aquarium.

Do not be tempted to lift any of your rocks off the base of the aquarium simply add the sand around the rocks.

If you did lift the rocks off the base of the aquarium and then place them back on top of the sand then this would cause compaction in the sand and the bed will not function.

With you adding the sand around the base of the rocks compaction can occur and more importantly the little beasties can migrate from the rock into the sand. It is important to have a huge diversity of life within the sand bed as they consume the detritus in the bed as well as ‘turning over’ the sand.

The pumps/powerhead can now all be turned back on again.

With you having a running aquarium system then you will no doubt get a sand storm in the aquarium. This will clear quite quickly.

Once the bed is in place if you removed and old sand from the aquarium then some of this can be placed on top of the new sand bed as this will help introduce the valuable little creatures into the bed.

Your job now is to feed the bed to ensure that the population grows and grows. Regular feeding will be required and can be achieved by simply placing a cube of frozen food daily on top of the sand bed. The food can be held in place by a stone, shell of something similar. Vary where you feed the bed and over time the population will increase and before long you will an exceptionally powerful filtration device – especially if you combine it with live rock.

I suppose that there is also a moral to this article as well as some information being provided in relation to the introduction of a deep sand bed.

The moral is that you are not always right. Listen to what other people have to say, take their advice and then make your own decision.

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