Sump Or Refugium?

All aquarists know the difference between a reef, mixed reef and fish only aquarium. However, confusion arises on occasion about the sump and refugium.

There are many systems of whatever type that include a sump. Usually they are put there in the design stage and this is really the easiest option, as feeding seawater to and from the sump is more easily arranged.

The sump is defined by the Oxford dictionary as ‘…a pit for collecting water etc’. That’s fairly accurate I suppose in relation to marine systems, one of the attributes of a sump is that it increases the net seawater gallonage of the system which is good for quality. In addition to this it permits items of hardware such as protein skimmers and heaters to be placed out of sight, which is good for the main display.

This is where the confusion starts. In addition to equipment, a sump could also be used for a deep sand bed (DSB) and could also grow macro algae. Then an addition could be made by using a partition and installing a ‘refugium’. The aquarist declares that he has a refugium.

I don’t want to be over-finicky, but is this correct? It is understandable certainly, as a refugium is a place where small life forms can live away from the predations of fish etc. Over and over it is said that small life forms are essential for the health of the DSB. There aren’t any fish in the sump so the small life forms are protected, so maybe it has become a refugium!

In the dictionary version I have ‘refugium’ is not given but no matter, let’s look at ‘refuge’. The definition of this is ‘…shelter from danger, pursuit or trouble.’ So the refugium is a specific not a general item.

Back to the sump then, as said it is primarily added to the system to increase net seawater gallonage and provide an area where heaters etc can go. If the aquarist wishes to add a DSB then fine and the same goes for macro algae. This makes the sump …a sump. It has been added for specific purposes, not one particular purpose.

A refugium is an additional aquarium or container that has been added to the system in the same way as a sump. However, in this case it is intended primarily as a refugium, nothing else. A fish only aquarium is an environment for fish, a mixed reef an environment for fish and corals. The refugium is an environment designed for small life forms. It keeps them safe from predation by fish and permits them to develop and flourish. At the same time, of course, it also increases the net seawater gallonage of the system.

So if the system is to include a sump and a refugium, there should be three aquariums. The largest one will be the display aquarium of whatever type, and attached to this and fed seawater by it will be a sump and a refugium. The major advantage of the two, apart from increased seawater gallonage, is space. There is more space for equipment in the sump if it is not being used for so many purposes, and there is more space in the refugium for the creation of the special environment.

Overall though, it could be argued that the above is a terrific example of nit picking! Truth of the matter is, the sump doesn’t have strict boundaries and could be and often is used for a DSB and macro algae, with lots of tiny life forms. These life forms are protected from fish predation so it is a refuge. The specific refugium is different because it is only that, a refuge, nothing else. The refugium, as it is for one purpose only, may well offer greater space for the created environment, which in turn permits more life to develop, which could mean a higher amount of live food (that which finds its way into the main display aquarium).

I would love to have a three tank system but haven’t the space. Those who have the space, great! Those aquarists who use a sump only, no problem, let’s not argue about a name.

---

How Long Should You Leave Refugium Lights On For

Refugiums are becoming more and more popular nowadays as people are starting to realise the beneift that they can have upon the aquarium.

Refugiums, as the name states are a refuge for animals to live without fear of predation. It is also an area where macro algae can be grown to assist in the removal of nutrients from the water.

In a normal refugium macro algae is grown to assist in the removal of nitrate and phosphate. In the refugium may also be a scattering of sand, a deep sand bed or even a mud bed.

Macro algae normally will only remove nutrients when it is actively growing and for this to happen it requires a light source.

The best light source to use is lighting which is correct for the growth of plants – this is normally in the lower end of the kelvin scale.

In the display aquarium the lights are left on for between 8 and 12 hours however how long should the lights be left on above the refugium?

There are two answers to this question:

1. The lights are left on for a 24 hour period. With this method the algae is allowed to grow continuously and therefore remove more nutrients from the water column.
2. The lights are lit in what is termed reverse light cycle. What this means is that the lights above the refugium come on when the display aquarium lighting goes off and turn off when the display aquarium lighting comes on.

So what do I recommend and why?

Both options are valid options however I would recommend option 2.

The reason for this is that I like to follow nature. In nature the grass beds are not subject to lighting over a 24 hour period – the receive light when the sun is out!

I also believe that the algae needs a ‘rest’. It requires a lot of energy for the algae to grow and if it grows continuously then problems may occur. This is not something that has been scientifically proven but is something that I believe could happen. It also needs to be remembered that in the refugium other organisms also exist. There will be various types of organisms which, like most life would prefer a period of darkness. I read somewhere, unfortunately I cannot remember where, that in a refugium which was provided with darkness the population of organisms grew however if the lights were on continuously the population did not grow as fast.

There is another area which is important and both of the above methods provide this – pH stability. When the lights go out above the display aquarium there is normally a slight pH drop throughout the hours of darkness. If the refugium is lit throughout these hours of darkness then the pH drop may be countered. As with anything in this hobby stability is key and this is just another area where this stability can be maintained.

So in my opinion the refugium can be lit of a 24 hour period or it can be lit on a reverse cycle however if I was to choose then I would choose reverse cycle for the reasons listed above.

---

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.

---

Caulerpa

Mention the word ‘algae’ to a marine aquarist and the aquarist’s face might turn white, before he or she spins round to look at their aquarium and ask, in a panicky voice, ‘Where?’

We are all aware of that concern: nuisance algae! The stuff that covers everything in long thin strands of green or covers with a thin sheet of dark red or black looking film. Nuisance algae can be combated or avoided in the first place. But this isn’t about nuisance algae.

This is about nice algae for the aquarium! In the marine world there are a lot of types of algae that could come under the word ‘nice.’ They are decorative and sort after. Aquarists who use live rock may have been fortunate to see some grow.

Of course there is one algae that is essential, and this is the single celled type called zooxanthellae, or symbiotic algae, which dwells in the flesh of corals.

The algae here is Caulerpa sp. This is green, though the shade of green can vary, and generally grows longish leaves (sometimes up to 12″) which have various ‘patterns.’ The algae spreads by putting out runners, from the top of which the leaves appear. Underneath are holdfasts, which look a little like roots. The roots are simply anchors, however, as the caulerpa feeds through the leaves. This macro algae is very useful to the marine aquarist for decorative and/or filtration purposes.

A great deal could be written but all that will be done is a general description of the main types and what they could be used for.

The first and probably best known is Caulerpa prolifera. The leaves are plain and have straight edges which taper to a point. The leaves are normally flat. Growth is fairly speedy.

Two more attractive types are Caulerpa mexicana and Caulerpa seratuloides. They both have leaves that look a little like bird feathers, with individual sections sprouting from the stalk sideways on both sides from bottom to tip. These types could show rapid growth.

A different appearance from the previous types is Caulerpa racemosa. It is often called grape caulerpa because of the appearance: the leaves are bunches of small grape-like growths attached to the stalks. This type is more slow growing and more difficult to cultivate successfully.

What can be done with caulerpa? For decorative purposes it would of course be in the display aquarium, where it can look very attractive. However, the aquarist must be sure it doesn’t outgrow its welcome as some can spread rapidly. I had some Caulerpa mexicana in a previous aquarium and it was certainly attractive, though I had to harvest it regularly to maintain control.

The other area that caulerpa is often found is in a sump. Aquarists grow it there so that it can act as a filter. As it is an algae, it uses the same nutrients that nuisance algae does, that is nitrate and phosphate. In doing so it robs any potential nuisance algae of food. Even if hobby test kits indicate zero (undetectable) for nitrate and phosphate, it could well be that there is a low presence. Planting a piece of caulerpa and watching to see if it grows is possibly an indicator. Obviously, algae in a display aquarium will also reduce nutrients.

As with all plants caulerpa needs light. Fluorescent tubes such as T5’s or metal halide bulbs should be fine, so growth in a display aquarium should not be a problem as far as this is concerned.

Caulerpa grown in a sump can be lit a little differently. A fluorescent light with reflector will suffice, the light is usually quite close to the seawater surface. There may be an advantage in using a tube that has a K (Kelvin) value that is lower than normal for a display aquarium, such as 6500K. Or a white marine type can be used, around 10000K. In addition there are two ways of timing the ‘light on’ period. First is to leave the light on all the time without any dark period, which doesn’t seem to have any detrimental effect on the caulerpa, and the second is to have the light on period when the display aquarium is in the light off period. The second option could assist with pH stability – pH could fall a little when the display is in the dark period, but with the caulerpa lit this is counteracted.

When planting in a display aquarium, try the type of choice and see if there is any success. If not, try another type. In the sump, it could be a good idea to plant more than one type and see which ’takes’ first.

Caulerpa should be harvested from time to time, always leaving plenty to continue growth. As the plant uses nutrients, removing the caulerpa in a controlled manner also exports nutrients.

The aquarist may find that the caulerpa in the display aquarium is disappearing. Have a look at algae loving fish such as surgeons and rabbit fish – they could be fat and very happy!

Important Note: Caulerpa in the aquarium is fine, decorative and useful. However, when harvesting, or simply removing caulerpa of any type it must not be thrown away into the sea. Caulerpa is invasive and can and is causing problems.

In some areas caulerpa is banned because of problems. Please check the position in your area before obtaining caulerpa.

For some information here is a link:

http://www.sccat.net/#the-caulerpa-information-center-1e86c5

---

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?

---

At What Times Should The Lighting Be On Above The Refugium

In the refugium we are attempting to grow macro algae. The reason for this is that as they grow they remove nutrients like nitrate and phosphate out of the water.

In a previous post I have discussed what type of lighting should be used so that you can get optimum algae growth plus I have also talked briefly about harvesting the algae from time to time.

One thing which I have not really touched upon is how long you should provide lighting for.

There are two methods available – one which I agree with and one which I don’t.

I shall cover the one that I don’t agree with first.

Option 1 – Provide Lighting Over a 24 Hour Period.

So why don’t I agree with this?

Basically it’s because it does not happen in nature. There are some aquarists who believe that providing lighting over a 24 hour period prevents algae crashes from happening. This is where all the algae suddenly dies and all the nutrients which are removed are released back into the aquarium.

To me this has never been proven. If you look at nature the algae beds in the sea are exposed to sunlight over a determined length of time. The same as provided for the corals. You would not leave your lights on for 24 hours to provide light for the corals so why do it for the algae.

I am firmly of the opinion that we should attempt to replicate nature wherever we can. It works in nature so why try to change it in our aquariums?

I also believe that the algae needs a rest!

There is another factor to this as well. This is that in darkness the micro organisms come out more and start to feed and reproduce. It has been noted by many aquarists that they have experienced a pod explosion when the lights are out for a length of time.

Option 2 – Provide Lighting Over A Shorter Period.

This is my preferred option.

I have covered some of the reasons above. i.e. lighting is not provided over a 24 hour period in nature so why do it in our aquariums and the factor of the little critters which we are providing refuge to.

So how long is a shorter period. Well it can be many things but the method I use is that the lights above the refugium turn on when the main lighting turns off above the display aquarium – i.e. the metal halide lighting. They stay on all night and turn off when the metal halides turn on the next day. This is sometimes called reverse sunlight lighting.

So why do I do it this way and not have them on at the same time as the metal halides?

Basically this is so that I do not experience a drop in pH over the nightime hours. The reason this happens is that when the lights are on photosynthesis occurs, carbon dioxide is used and oxygen given off into the aquarium and the pH rises or in this case remains stable.

Stability as we all know is a major factor we are all hoping to achieve.

If we had the refugium lights on at the same time as the main display aquarium when all the lights went off there is a possibility that the pH will drop.

So that’s why I prefer option 2 – it simply makes sense to me.

Another thing that I also do is occasionally turn off the lighting above the refugium for a couple of days. I have found that when I do this I get a lot more ‘critters’ in the refugium. The more ‘critters’ there are the happier I am!

---

What Lighting Should You Use Above The Refugium

A refugium can be made from many things in the aquarium but for the concept of this article we shall classify a refugium as an area which contains a sand covering and macro algae being grown.

This type of refugium allows for two things to be completed :

1. A safe refuge for for animals to populate without fear of predation.
2. Excess nutrients to be removed by the macro algae growing.

The refuge aspect is created automatically simply by not introducing fish or other animals with feed on the little ‘critters’ into the area, For the excess nutrients to be removed though the macro algae needs to grow and for that it needs light.

Can you just use any light though?

Not really.

As we are growing plantlife we need to use lighting which is designed for this purpose.

For reference the normal lighting we use above a [tag-tec]saltwater aquarium[/tag-tec] is between 10,000 kelvin and 20,000 kelvin so can we use that.

We could but that kelvin rating is not suited for plant growth – it is suited for corals. Corals require lighting which is in the blue to violet range of the spectrum. Although it would work the macro algae would probably grow slower than if you used lighting designed for aquarium plants. Macro algae (and the majority of aquarium plants) prefer lighting which is in the red to orange range of the lighting spectrum.

For this reason it is better to attempt to locate lighting which is between the 5,000 kelvin and 10,000 kelvin rating with the lower end being the preferred end.

The interesting aspect here is that you do not have to utilise lighting which has been designed for aquariums. It is the kelvin rating we are interested in and luckily for us there are loads of house based lamps in this area.

Simply pop along to your local household store and check out the lights, read the label and see what the kelvin rating it.

Of course if you do not want to do this then just go to your local fish shop and ask for a blub which is designed for aquarium plants.

---

Next Page »