The question came from a beginner aquarist who openly admitted that she didn’t have much experience. In fact, she had done precisely four routine seawater changes with her new aquarium. The aquarium, a fish only, was not overstocked, if anything it was understocked. She was a little fed up; the excitement of actually seeing some life in the aquarium after all the patient waiting when the system was being put together was being spoilt by the dreaded algae. I was unable to see the aquarium.

Basically she had done seawater changes and after each one she advised ‘red’ algae had gone bananas. That’s what she said; I don’t think it could have been quite as bad as that!

Many aquarists have problems with various types of algae, particularly when inexperienced and when the aquarium is in its early days. I was surprised that it was red algae causing the trouble. Usually it is green hair algae, or so-called slime algae or smear algae (a thin sheet that slowly covers rocks, sand etc). Slime algae can be ‘reddish’, very dark and appear red nearly black. Another type is diatoms that are usually more golden brown in colour.

Red algae can be calcareous and branching or encrusting, or have flexible ‘leaves’. These algae types are often sort after by aquarists as they are decorative. In the red algae family there are over 4000 types. The algae though had been identified as a problem and not decorative so it cleared these types away. So the algae in question had to be a problem type, but what? Green hair algae was obviously not the answer.

When an aquarium is first started up diatoms often appear. They could cover rocks, sand etc. The diatoms rely on silicates in the seawater – if the silicates go so do the diatoms. If they appear then die back, the silicates are used up. If they then re-appear at a routine seawater change, then more silicates have been introduced. The fresh water source could be suspect. Dry sea salt does not usually cause this type of problem.

Smear or slime algae is a bigger problem. It can be quite difficult to erase but this can be achieved. The presence of smear algae suggests excess nutrients in the seawater, even in a new aquarium. Also smear algae does not like strong currents – it often tends to appear in quiet areas of the aquarium, though just to be helpful it can appear in more turbulent areas.

10% of the net system gallonage is the guideline amount for routine seawater changes, until the actual needs of a particular aquarium are known. The changes being done were of this amount.

Possibilities would have to be narrowed down, so the first suggestion was that seawater tests should be done, that is, nitrate and phosphate. A request was made to test both the seawater in the aquarium and the new seawater made up for a routine change. Ideally, in the aquarium nitrate should be as low as 10ppm (parts per million) or less particularly for a reef aquarium, a fish only could be higher but should still have nitrate minimized. Phosphate should not be detected at all hopefully, but at least the level should not be more than 0.03ppm. If it is higher, say 0.10ppm, it is too high. In newly made up seawater there shouldn’t really be any presence of nitrate or phosphate. Nitrate and phosphate are known problem algae nutrients, thus the need for control.

It turned out that nitrate and phosphate were present and ‘a little too high’, levels were not given. The seawater destined for the routine change was also tested – the same for nitrate. Now then!

So on to the next possibility. This follows the clues given – the algae become more apparent after a routine seawater change and nitrate was present in the new seawater. A check was suggested of the freshwater being used.

The information arrived that the nitrate level in the freshwater was ‘high’. Maybe this was tap water, the most likely, or it could be local spring or well water, I don’t know. Nor was the actual level given. However, ‘high’ in this instance meant ‘too much’ and this seemed to be the problem that needed to be dealt with.

Tap water is not necessarily as pure as might be thought. In agricultural areas there could be excessive nitrate levels. There could also be heavy metals, pesticides, phosphate, chlorine, chloramines and so on. The water is made safe for human consumption; there are regulations as to how much of what is permitted.

The suggestion was made that fresh water should no longer be used from that source, and that a reverse osmosis (RO) unit should be obtained. The RO unit is a membrane that only permits pure water to pass, or nearly so. The purity is usually about 95 to 98%. It is important to have a unit that incorporates a carbon filter at the front end; this protects the membrane as chlorine is removed. Chlorine could damage the membrane. A sediment filter is often incorporated before the membrane as well. RO units come in various ‘gallons per day’ sizes, one needs to be picked that is suitable for the size of the routine seawater change. RO units are very reliable and only require the carbon filter etc changing from time to time in accordance with the manufacturer’s directions. They are not particularly expensive either.

It is worth using high quality fresh water obviously for the welfare of the livestock; also dry sea salt is not cheap. Dry sea salt manufacturers produce salt that is free of nitrate and phosphate – why spoil this with poor fresh water?

Much later on it was learned that an RO unit was in use and though nothing had happened for a while, in time the algae (‘slime’ I assume) started to reduce and the aquarium became clear of it.

This seems a good demonstration that the aquarium will reflect what it receives. Feed in algae nutrients and algae could appear. In this case all turned out well.

Algae to an aquarist often mean trouble. It is one of the continuing ‘don’t wants’ of the aquarium. Hair algae, slime algae, yuk, no thanks! Then there’s the algae that’s purposely grown in a sump to aid filtration, usually Caulerpa.

The algae referred to here is none of the ‘horribles’, or Caulerpa, but the ‘reefy’ encrusting algae that is welcome, by me anyway.

At first when the aquarium started I used to keep all four side glasses clean. A considerable time later I noticed that encrusting algae had taken hold in a back corner. A closer look showed that it seemed decorative and welcome, so the algae’s impending doom with a scraper was averted. One end of the aquarium was not cleaned at all; it was left to its own devices. The glass turned green, the usual stuff, but despite twitching with the urge to clean it off, it was left alone. Over a few weeks it gradually turned dark.

I thought about this for a while, and then increased the alkalinity of the seawater from 2.5 meq/L to 4.0 meq/L. The reason for this action was that it had been anecdotally reported that bad algae grew poorly with higher alkalinity, but encrusting decorative algae does better. Having done this I monitored the corals carefully but nothing untoward occurred.

As time progressed the glass that had been left turned into dark, medium and light green patches. It also developed lots of tiny white pimples on it. It looked great.

Having obtained reassurance by this ‘experiment’, I left the back glass alone and just kept the front and one end glass clean. This was probably going to happen anyway as the corals were larger and getting to some areas of the glass had become difficult. The algae continued to develop and then covered the stated glass panels completely. The aquarium looks really great with this natural decoration in place. The original blue of the back glass can no longer be seen.

The alkalinity level has been maintained at 4.0 meq/L for years and the encrusting algae do seem to appreciate it.

I did note that algae over an area of about 2 square inches had come away from the glass and fallen down; it could be seen on a rock. The glass where it had been was clean. The fallen alga was quite thick, about 1/8 of an inch, so I assumed it had simply lost adhesion, glass is hard and smooth. Sure enough, the clean area was soon being taken over and is now once again covered.

Something else I have noted is that tiny shrimps, similar to the ones that scurry over the rocks and sand at night, take refuge behind some areas of the algae. Close inspection shows that the algae appears to be slightly loose in place – I wonder if the beasties have burrowed their way in or simply taken advantage.

Over time one or two additional patches of encrusting algae have come away and are growing back. Taking a photograph of the algae is difficult as corals tend to get in the way, however I did find one area that is reasonably open and used that. The patches on the left can be seen, in process of re-covering. Original algae can also be seen. Incidentally, the attached ‘leafy’ algae that can also be seen aren’t what I’m talking about, but are also very decorative. It is also very friendly in that if any does grow where it isn’t wanted the whole ‘leaf’ easily comes away for removal.

Algae can be the aquarist’s friend, adding a natural decorative background and increasing the overall attractiveness of the aquarium.

Mention the word ‘algae’ to different marine aquarists and the reaction could be mainly one of two, a look of horror perhaps bordering on panic or a smile and a nod. It all depends.

To some aquarists algae is most definitely a foe. These aquarists are, in the main, novices who are gathering experience and have found out the hard way the consequences of over feeding, over stocking, or over lighting. There could even be a combination. One consequence is long hairy green stuff waving in the currents as though it is making fun of the suffering aquarist. Green filamentous algae can spread to such an extent it overgrows the whole aquarium! It seems to be hardy too, as even if the nutrient level is reduced the monstrous stuff seems to survive for quite a while. It takes the nutrients out of the seawater of course which is the only saving grace I can think of. No, there’s one more, which is that it is food for some fish. Nevertheless, it is not required in abundance.

Similarly, slime alga is a problem. This time it is like thin semi-solidified goo on surfaces which is capable of suffocating the life out of anything it covers, again definitely not required. Fortunately it can be siphoned out at routine seawater changes but tends to linger for a while.

So who smiles at algae? It has to be those aquarists who have control of their aquarium conditions. Seawater parameters are as they should be and not permitted to be anything else. Some of these aquarists use algae to combat other algae, which sounds like justice to me! For example, nitrate and phosphate are implicated in the growth of nuisance algae. The same nutrients are necessary to some decorative algae. So, take some decorative algae, such as the Caulerpa macro type, and grow it in reasonable quantity in favourable conditions. If the bad algae is being physically removed and the good algae is taking in nutrients and in favourable conditions, which will lose out? It is likely to be the bad algae. Many use the system and it is definitely helpful.

Have a look at the imported photo with this text. Is that some of the hairy stuff I see?

I’m going off track a little but remaining with algae. Here’s another positive for algae which could develop beyond the intended stated use in a few years. Hope it proves to be of huge benefit!

http://coast2coastam.net/?p=198

Maintenance was carried out as usual without any problems. I noticed a coral (a toadstool) was loose and breaking away from its anchor point. So when the partial seawater change had been completed – the last task in the maintenance – I turned my attention to the coral.

It was simple removing it from the rock. The reason it had become loose was because new corals were growing from it and the new ones used the same anchor point. This meant that the seawater currents had more to affect causing more of a strain. I got out a cocktail stick and positioned the coral in a location where it could spread more easily though still in the same area.

As I bent to complete the re-positioning I noted a group of new toadstools that were growing. Great! Then I noticed at the rear of the aquarium on the rockwork some algae commonly called ‘sailor’s eyeballs’. The proper name for these is Ventricaria ventricosa. These are thought to be maybe the largest single-celled organism on the planet. Each cell is filled with carbon monoxide, a toxic gas* – this doesn’t normally cause trouble though. The cells are also filled with a large number of spores. After sufficient growth the cell bursts and these spores are released – not wanted!

I wasn’t alarmed as I have dealt with these little perishers on and off for a long time. They are quite attractive really, but it is the extent they can spread that is the problem. It was when I noticed the spread that immediate action was required; there must have been 100 or more of them growing. I hadn’t noticed them until I had to lean over the aquarium at an unusual angle to fix the coral.

So off I went to get my very sophisticated anti-blob kit – a length of silicone airline fastened to a short length of rigid airline. After emptying the old seawater from the bucket I commenced siphoning. The algae are destroyed one by one by pressing the end of the rigid airline on them until they burst. Any spores are hopefully drawn into the siphon tube by the seawater flow. This destruction process becomes more efficient with practice. I can achieve quite a speed as, as said, I have been having small skirmishes with them for a long time. It took about ten to fifteen minutes and the job was done.

They will be back of course as there isn’t a way that all of them will be removed, there are so many nooks and crannies in a reef aquarium. The majority will have been destroyed though.

The event reminded me to check from time to time areas of the aquarium that are hidden from a normal viewing angle.

What a shame it is a nuisance though. The appearance of the algae is said to be a good sign as it will only prosper in excellent seawater conditions*, that is, seawater lacking in phosphate and nitrate. Also, as stated, it is quite decorative.

Below is a link to enable identification of the algae. The images can be clicked on to enlarge them.

http://www.poppe-images.com/images/search_results.php?category=Algae&species=Ventricaria%20ventricosa

(Reference: Baench Marine Atlas. Helmut Debelius & Hans A. Baensch)

Some of these life forms end up in the home marine aquarium. With the natural seas being so stable it follows that for success the conditions on the wild reef should be duplicated as near as possible, and conditions provided that successfully permit life to function and be healthy.

Seawater quality is the number one on the list of ‘must haves’ for success so it follows that the seawater used should be as close as possible in make-up to the natural kind. In much earlier days aquarists would obtain some constituents – not all of them by any means – from a chemist and mix up a brew. Livestock existed in this fairly well for a while but trouble usually appeared. Nowadays there are many high quality dry salt mixes available which the manufacturers state equals the natural type. Be that as it may, the appearance of these dry salt mixes has brought the successful maintenance of a marine system within the reach of every aspiring aquarist provided the interest in the hobby is maintained and the requisite maintenance is done.

Seawater is a mix of many things, some of them present in major amounts, others in trace amounts, and more with a very tiny presence. So for the benefit of anyone interested there follows a list of the make-up of seawater. There is clearly no requirement of any kind for an aquarist to know them but as said it may be of interest. It could also be of use for aquarists who wish to maintain natural levels of important parts such as calcium etc.

Major Elements. (All measurements in mg/l)

Trace Elements. (All measurements in ug/l)

Constituents with a tiny presence.

(Reference: ‘Baensch Marine Atlas’. Helmut Debelius & Hans A. Baensch)

Of course not all algae’s are bad; in fact they could be the aquarist’s friend. There are many forms of decorous algae. Caulerpa is a larger form of algae that is often used by more experienced aquarists to reduce nitrate and phosphate, as it uses the nutrients for its growth which of course means that other nuisance algae cannot. When used this way it is usually kept in the sump under individual lighting.

The algae types that worry aquarists the most are green filamentous and smear algae. Filamentous green algae take the form of very thin strands which are close together and could be up to 8″ (circa 20 cm) long. If unchecked it could cover all the rock and sand. Smear algae, also known as blue-green algae (though it comes in more than one colour variation), properly known as Cyanobacteria, which is often a dark reddish brown appears, as the name suggests, as a thin covering that is really unsightly. If unchecked this thin film could extend over much of the aquarium décor and smother all underneath.

There is another algae type that often causes alarm and it often appears in a newly set-up aquarium, seemingly – from anecdotal reports – particularly where a decorative sand bed (or possibly a deep sand bed) is in use. It is not a definite appearance however; quite a few aquariums never develop it. It could be a nuisance in older aquariums under certain conditions.

This algae is diatoms. Sometimes they are referred to as brown algae, but this is incorrect, brown algae is another type altogether. The algae could also be mistaken as a form of smear algae as the aquarium décor could be covered with a thin layer. Again, smear algae has nothing to do with diatoms.

Diatom algae rely on silicic acid being present in the seawater. If this remains present in any amount it will be extremely difficult to get rid of the diatoms. Tap water could contain the acid in a sufficient amount to support the algae – if it doesn’t it is likely that it will not appear. If there is a sand bed present maybe silicon is present?*

Wandering off-course for a moment, diatoms have a really wonderful cell structure. I have only seen pictures in books. They could be circular, triangular, oval etc and have intricate patterns within the cell that are individual. I don’t know, but I doubt they are singularly unique, but there are many variations. The cells, which are constructed of silicon, don’t degrade and are in fact used in diatomaceous filters. The media is simply made up of these cells.

Anyway, if the aquarist has an invasion of diatom algae then the first thing to do is wait. After a week or two the diatom problem will often die back and cease to exist. The die back usually is not instantaneous but occurs over a period.

If the problem is getting worse, and/or there isn’t any die back, then it is likely that silicic acid is being supplied. I’m not sure of the sand bed bit, but perhaps silicon content within the sand bed is the culprit. If so, then the silicon should exhaust?* Obviously the aquarist should not be tempted to change the sand bed as this could well make matters worse or extend the period when the diatoms are present.

If the aquarist is using tap water then he or she could have the water tested for silicic acid content. If routine seawater changes are being done, as they should be, and the acid is present in the water then fresh supplies are being provided and the diatoms will not go away.

Another way to deal with the tap water is to use reverse osmosis (RO) water. This is tap water that has been filtered through a very fine filter and much of the unwanted content of the water is removed. The purity of the water when leaving a RO filter is generally from 95 to 98%. The use of RO water is recommended whether there is a diatom algae problem or not. RO filters are available to the hobby commercially, are not particularly expensive, and are a good investment.

So, despite the attractive individual cells of diatom algae, the alga is not wanted. Of the nuisance algae types this is probably the easiest to deal with.

(* I have never seen any ‘official’ or science proven reports about the affect of new sand beds in marine aquaria)

It is important to understand in the first instance why algae takes hold and grows in the aquarium.

All algae require an energy source. This energy source could be a particular colour temperature in the light, a nutrient in the water etc.

Therefore the algae outbreak could be due to the lighting not being replaced and the incorrect colour spectrum being transmitted into the aquarium. Some algae like this particular temperature and then grow. The light to the human eye will probably look fine however unless you perform a specialist test you will not know. The best thing to do is ensure that you change the bulbs at the correct time period based upon manufacturer’s recommendations.

The second and probably the most common one is where algae feed upon nutrients in the water. The most common nutrients and nitrate, phosphate and silicates. In this scenario especially for nitrate and phosphate it can be hard to locate. The reason for this is that the algae are taking up the nutrients from the water column and therefore when a test is performed the parameters appear to be ok. As soon as the algae is removed from the aquarium the levels start to increase and the algae takes hold again.

It is a vicious circle unfortunately.

As the saying goes though – prevention is better than cure.

The best prevention is to ensure that the equipment in the aquarium is correctly maintained and replaced if/when required as well as the water parameters being kept at the highest possible standard.

A very useful part of obtaining these parameters is the reduction/removal of nutrients. An excellent way to reduce and/or remove nitrate and phosphates is through the use of natural based control.

This natural based control could be live rock, deep sand beds, mud beds, refugiums, mangroves etc.

Live rock for example is exceptionally powerful at filtering the aquarium and if enough high grade quality is purchased then it can also assist in the reduction/process of nitrates.

It is my opinion that there are two natural based packages which can be used for both filtration and nutrient export.

These are:

1. Live rock combined with a deep sand bed – This allows for efficient filtration of the aquarium via the live rock and also for nutrient export via the deep sand bed.
2. Live rock combined with a refugium – This again allows for the efficient filtration of the aquarium via the live rock and also for nutrient export via the refugium where macro algae is grown.

In the refugium example above I personally find it interesting that you can use algae to control algae. The reason this can be performed is that the algae which you are growing in a separate aquarium can be harvested from time to time. The algae removes nutrients from the water and uses this for growth. When the algae is harvested from the aquarium the nutrients are removed as well. As you are not removing all of the algae then the remaining algae feeds upon the nutrients in the water and maintains these parameters at a low level. Because the algae is located in a separate aquarium no or minimal algae outbreaks should occur in the main display aquarium. This is not to say you will never receive any because you might however it severely reduces the possibility.

These are not the only methods which you can use as there are many more. Mangroves for example are very powerful but they are very slow growing and therefore reduce the nutrients at a slower speed.

The aquarist, however should never rely upon these techniques and needs to ensure that the correct care and maintenance is still employed, the fish are not overfed etc.

Simply put in response to the question in the title of this post – yes natural algae filtration does work as long as it is properly implemented and cared for.

Follow nature and keep it simple.

When the home aquarium is first started everything is new. All the equipment, the sand, the rocks, the water etc are new. The aquarium needs time to settle in.

A good example of this is the sand. Quite often near the start the sand can become covered in what looks like a dusty brown covering. Quite often this is due to the silicates in the sand. When the silicates are all used up the algae simple disappears – quite often overnight.

As already said though an algae bloom can happen at any time especially if the water quality is not maintained at optimum quality. A couple of nutrients which can cause problematic algae to occur is nitrate and phosphate. The trouble in this instance is that the algae is using up the nitrate and the phosphate in the water therefore when the aquarists checks the parameters they show quite low, however behind the scenes there is a potential problem.

Another area is not looking after the equipment correctly. Two areas which spring to mind are the protein skimmer and the aquarium lighting.

If the protein skimmer is not maintained correctly then not all of the dissolved organic substances etc will be removed from the water and will be processed by the aquarium filtration and will therefore create nitrate etc which otherwise you would not have had.

If the light bulbs are not changed in accordance with manufacturers recommendations then the lighting will be below ‘par’ and could be producing lighting which is at the wrong end of the spectrum and algae which likes this type of colour could start to thrive.

There is another aspect which springs to mind and that is water flow. If there is not enough water flow in the aquarium or even in areas of the aquarium then algae can start to grow in these areas, cover the rocks perhaps even the corals.

The trick is to ensure that you maintain the aquarium correctly – perform all the required care and maintenance and attempt to keep the water at as high a quality as possible. Doing this however does not guarantee that you will not get any algae growing however it should reduce the likelihood of one occurring.

All algae have a food source. If an algae outbreak does occur the best thing to do in my opinion is identify the type of algae it is, identify what this type of algae feeds upon and remove its food source. Once the food source has been removed the algae will start to disappear.

There are also a lot of ‘quick fixes’ on the marketplace at present. Ones which promise to remove algae ‘magically’. Whilst I am sure that some of these do actually work are they just masking the problem and as soon as you stop using it the problem will re-occur. I personally think so. In my opinion the best thing to do is look after the aquarium correctly.

A lot of aquarists give up this hobby and the majority do so due to algae outbreaks. When thinking about setting up the aquarium they picture and aquarium which is always clean. They soon find out that this is not the case and go from outbreak to outbreak and eventually they get fed up and give up.

The internet is a huge source of information and fellow aquarists are always willing to help other aquarists. If you do experience an outbreak then the first thing to do is check all your water parameters. If there are any areas of concern then these should be rectified and hopefully the algae will go away. If not then the next thing to do is check the equipment to ensure that it is all working correctly and if required to be replaced has been.

If after doing this the algae is still apparent then pop to your local fish shop, speak to a friendly aquarist and ask their opinion. You will find that the majority of people are prepared to help out. If you do struggle then as said the internet is a source of great information. In this instance probably a forum or social community would be your best bet as you will be able to upload a picture of the algae where other hobbyists will be able to identify it and inform you of its food source. From this information you will be able to remove the food source from the aquarium and the algae should go away.

Of course you may get another outbreak. There are some aquarists who never have one – my dad John is one, he has never had an algae outbreak in his aquarium but then I have never seen another aquarium with water quality at the level he keeps his maintained at. Makes me jealous every time I see it!

The good thing about algae outbreaks in that each time you get one you learn something else about this hobby. This is now information that you can use to assist others if they get one and if you get another one then you will learn again.

As we always say – ‘in this hobby you never stop learning’.

There are many reasons as to why people give up. This could be personal finances, time, knowledge and many more, however a prime candidate unfortunately is algae.

Algae in the aquarium can look nice however in time this once ‘nice looking’ algae can turn into a pest and make the aquarium look unsightly. Before long the algae starts to cover the rocks, the sand, the glass and more. Every effort is made by the aquarist to clean this up perhaps by manually removing it, performing water changes, checking the water parameters, researching the possible causes etc however once one algae bloom is sorted before long another one may appear.

I appreciate that at this time the aquarist may become disheartened. I know I have been through this stage and can honestly say that algae blooms are a pain.

When people look into starting a saltwater aquarium they imagine an aquarium full of corals and fish which are so striking in colour and movement that the appearance of this unsightly algae is new to them. It is not what they wanted and try as they might it simply will not go away.

First to come may be a slight brown dusting of algae initially over the sand, second may come what looks like slime over the sand, perhaps the rock, after this long hair like algae may appear on the rocks and glass. Later algae which look like balls may appear!

It’s no wonder why aquarists consider giving up when the dream of a spotless saltwater aquarium is suddenly flawed with dirty looking algae!

Each of these different aspects of algae feed upon a different type of nutrient in the water. The trick to understanding how to clear the aquarium of the nuisance algae is to understand what it is feeding upon.

This is where the hard part starts. The reason for this is that since the algae is feeding upon a certain nutrient or nutrients in the water then a water test may not how this parameter as being a problem. A good example of this is phosphate. Phosphate is a common food for problematic algae however when a water test is performed the result is ok. This could be because the algae does not feed upon this type of nutrient or it could be that the algae has removed enough from the water for it not to show up on a water test!

The best thing to do if you encounter an algae bloom is determine what type of nutrient the algae is feeding upon and then remove its food source. For example if you have algae which is long and wavy then this is probably hair algae. Hair algae likes to feed upon nitrate and phosphate. In this example the best thing to do is attempt to reduce the nitrate in the aquarium by checking your feeding regime and increasing the amount of water changes performed to dilute the nitrate in the water column. To reduce/remove the phosphate levels it would be beneficial to introduce an element of phosphate remover for example a product like Rowaphos.

If you remove the food that the algae feeds upon then the algae bloom itself will reduce.

At the start of an aquariums life you need to remember that everything in the aquarium is new. All the pumps/powerheads will probably not have been submersed in water before, the sealant is new, the sand will be straight from the bag, the water will be sterile etc etc. From some of these certain elements may become evident in the water. A prime example of this is silicates from the sand – the slight brown dusting you see over the glass and sand is quite often caused by this. This aspect of algae quite often feeds upon silicates and will exist until its food source is exhausted.

I have seen aquariums entirely coated in this type of aquarium simply clear up overnight purely because the food source has gone.

In this example the silicates from the sand becomes exhausted and therefore the brown dusting disappears perhaps never to be seen again. In other areas if the aquarists is not diligent and does not perform the correct care and maintenance post identifying the food source then the algae blood can and perhaps will re-occur. There is no point in locating a problem, resolving it simply to allow it to raise its ugly head again.

The majority of aquariums when started do go through various algae blooms. This is the aquariums ways of becoming settled. Within time if the aquarist is patient and performs the correct care and maintenance then the blooms will slowly subside – hopefully never to appear again.

For all you new aquarists and the aquarists who are currently attempting to deal with an algae bloom I and many other aquarists understand what you are going through right now. The two things I can say is be patient and identify the bloom you are having issues with, identify its food source and eliminate it.

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