Diatom Algae

Algae! Now there’s a word that can raise very mixed emotions in a marine aquarist. Even if the aquarist is a newcomer to the hobby, if plenty has been read in research he or she will be aware of the dangers.

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)

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Tags: Algae, Aquarium Maintenance, Care, Equipment, reverse-osmosis, Water Quality

Coralline Algae Is Not Supposed To Be White

Coralline algae in the marine aquarium in my opinion makes the overall appearance much more attractive and natural.

There are some people who dislike coralline algae and each to their own. I have a personal hatred to having any on the front glass and as soon as I spot any out comes the blade to scrape it off!

Coralline algae comes in a vast array of shapes and various shades of pink/purple as well as other colours - there is one colour that it is not supposed to be however and that is white.

Coralline algae when white basically means that it is either dying or unfortunately is actually dead. If the entire area is white then it is dead, however if either the outer or inner areas are white and the rest still has colour then it is dying.

The white colour is basically the underlying carbonate structure of the algae - very similar to a coral which has expelled its zooxanthellae.

So how can this happen?

Quite a number of things really. It could a be a shift in balance of an important element - for example a drop in Kh in the aquarium. It could be due to the light bulbs being changed above the aquarium and the lights are now brighter. It could be the introduction of new lights. It could be a reduction in water flow. It could be not enough actinic light - the list goes on and on.

There will always be some area(s) in the aquarium where an area of coralline algae goes white. This cannot be prevented as things change inside the aquarium. If coralline was once thriving in an area of high water flow and the water flow is changed then the coralline algae may no longer thrive. I would not worry too much about the occasional area of dying coralline algae but if more than ‘a bit’ starts to turn white then this could be cause for concern.

Some aquarists worry when they see small white spots appearing on the coralline algae. In these cases the area could do with some closer inspection as this might not actually be decline it could actually be worms living on/in the algae.

Rather than go into how to prevent coralline algae from turning white I think it may be beneficial to look at how to actually increase coralline algae growth in the aquarium. If you understand what you need to do to encourage growth then you will hopefully see what is missing if some areas start to go white.

So how do you promote coralline algae growth?

First of all coralline algae does not like bright white light but really like actinic lighting. The first thing you want to consider is increasing the amount of hours that your actinic lights are on for. This is very simple to do by simply changing your timers so that the actinics come on one hour or so earlier and turn off later. Another thing you may want to consider and this does depend upon what else you have in your aquarium is increase the amount of actinic light and reduce the amount of white light.

The second thing is that you want to maintain your calcium at around the 400 mark. Coralline algae is a calcerous algae and therefore needs calcium to be able to grow and expand. As the coralline algae is growing it will deplete the calcium content in the water and you will need to add calcium additives or some other type of supplementary measure to keep calcium at this level.

Magnesium is the next consideration. This level should be maintained at around the 1300 mark. Again additives, supplements etc can be added to the aquarium to maintain this level.

Another element and in my opinion the most important one - strong water movement. Coralline algae does appear to grow better in areas of high flow. Have you noticed in other people aquariums that it appears to grow on powerheads, pumps, overflows etc. Water flow - important for corals, live rock etc but also important for good coralline algae growth.

The final aspect and a word that is said in every aspect of this hobby - patience. You will need to be patient as the coralline algae will not grow and colour up overnight. It will grow slowly at first and probably be so small for a while that you will not even be able to see it. Then after a while it will start to spread covering rockwork, pipes, glass etc and in the end, like me you will be scraping it off the front glass as soon as it appears!

There is another area that needs to be covered and that is the actual introduction of the coralline algae itself. Strangely enough it cannot grow if it is not already anywhere in the aquarium. A good piece of premium live rock will suffice as a seed. What I do when I am attempting to make the coralline spread is remove a piece of live rock from the aquarium and scrape it with a scalpel allowing the scraped coralline to fall back into the aquarium. Where it eventually lands it will hopefully attach and grow. Another method that some people do is not use live rock but use what is called ‘live rock grunge’. GARF manufacture and sell this and from what I have heard people have had amazing results. This method is particularly useful if you do not use live rock in your aquarium and have for example home-made rock or another type of inert rock.

The majority of aquarists aspire to having coralline algae which is a really deep purple in colour. It needs to be noted that you cannot pre-empt the colour that the coralline algae will be. You could purchase a piece of premium live rock which is covered in beautiful coloured coralline and over time it turns into a lighter shade. On the other hand you could purchase live rock covered in a light shade and it turns into a deep colour. The colour depends upon the actual parameters in your aquarium, the water flow, the lighting etc. Every aquarium is unique and that is one of the great things about this hobby.

It also needs to be noted that coralline algae is not always a purple/red colour. It comes in a lot of colours - green, yellow etc however a purple colour is normally the dominant one. One colour which you don’t get however is white - well not that I have ever seen anyway!

There are some products on the market nowadays which are designed to accelerate coralline algae growth. One that I have heard of is one called Purple Up Coralline Accelerator - I have never personally used this or any type of these products as I prefer to do it ‘naturally’ and therefore am unable to comment on their effectiveness even though I have heard that they are quite good.

So if the coralline algae in your aquarium starts to go white then basically ensure that all of the above is correct and correct the one(s) which is off the mark.

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Tags: Algae, Aquarium Maintenance, Care, coralline-algae, Equipment, Water Movement, Water Quality

Does Natural Algae Control Actually Work

At some stage in practically every aquariums life it will become the end result of an algae outbreak. Quite often these outbreaks simply disappear on their own, however on some occasions they simply will not go away and no matter what the aquarist does they simply return.

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.

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Tags: Algae, Aquarium Filtration, Aquarium Maintenance, Care, Equipment, Problems

Why Do Algae Blooms Occur In The Home Aquarium

Algae blooms can occur at any point in a home aquariums life but normally algae blooms occur during the start of the aquariums life.

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’.

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Tags: Algae, Aquarium Maintenance, Care, home-aquarium, marine-aquarium, Problems, Water Quality

Algae - It Makes A Lot Of People Give Up

Thousands upon thousands of potential aquarists make the decision to start a saltwater aquarium, be these fish only or reef aquariums all around the world. Unfortunately a lot of these aquarists ultimately give up in this amazing hobby.

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.

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Tags: Algae, Aquarium Maintenance, Care, Equipment, nitrate, phosphate

Sigh!

I really like my soft coral reef - all the time it developed over the last 5½+ years and how it is now. It is really full of a diverse range of corals coloured various pastel shades, the tall ones swaying in the currents. There is hardly any rock to be seen as it is nearly all covered. The rear glass and one side are decorated with varying shades of algae, purple, dark and light green, brown and, thankfully, not a trace of the nuisance stuff.

Three fish were originally housed, a flame angel (Centropyge loricula), a flashback dottyback (Pseudochromis diadema), and a blue devil damsel (Chrysiptera cyanea). They were all chosen as they would be able to stand up to each other’s aggressiveness. This proved to be the case; the flame angel became boss quickly. They were all introduced to the tank at the same time.

The dottyback at 2½ years disappeared and I have no idea why. The fish was well fed with rounded body, good fins and clear eyes. Perhaps it got itself stuck in the rockwork somewhere? As said I haven’t a clue as to the reason. To date it hasn’t been replaced as the other two are really well settled healthy and happy. I don’t want to upset the equilibrium, and am also afraid that two quite aggressive fish, well established, could pick on a newcomer with sad results.

The system started off with canister bio-filtration (yes, I know, but I’m coming to live rock). There’s a skimmer (of course!) and also a home-made reverse flow anti-phosphate reactor. There’s also a home-made anti-nitrate sulphur based reactor.

As time passed I wondered if there would be a need for the de-nitrator any more. It was originally attached because of the presence of canister filtration and the consequent production of nitrate. The seawater never showed any trace of nitrate. The rocks that had been used for the reef were not live but inert hard porous types, locally called Grotto rock. I don’t know the proper geological name. Anyway, the rock became covered with all sorts of growths and looked after time had passed very much like live rock. I decided that the nitrate was being dealt with by the now live rock. So switch off the de-nitrator then. This was done but only after I’d dithered for another few months, and after the device had been switched off I needed to do nitrate tests regularly to assure myself all remained well. It did, and to date there hasn’t been any nitrate detected.

The anti-phosphate reactor is still running and will not be stopped. There has never been any phosphate detected.

Originally I ran two Eheim canister filters containing bio media. One has had the media removed and now runs empty - I am considering what to do with this, if anything. The other still contains bio media and I am considering removing that too. The rocks will contain sufficient bacteria, but I am always cautious. Once the second canister is empty ammonia checks will be done for a while, again to confirm that bio filtration is adequate. The livestock, all corals and two small fish, is not exactly a heavy load.

I sit and look at this system having seen it develop and continue to develop and feel really pleased overall. It’s so interesting, corals and fish as said, but also tiny life that darts about on the rocks and deep sand bed particularly at night.

Being so pleased, what’s the big ‘Sigh’ about? Well, it’s about defeat. At least, defeat up to now.

I’ve had two problems. One was those little green balls, known as Sailor’s Eyeballs, properly known as Ventricosa ventricosa. It is a green algae that is thought to be the largest single-celled organism on earth. It’s also quite attractive, at least it is until it begins to spread. Inside each ball are spores - if the algae is broken the spores go all over the place and new algae grows. In time the algae can overwhelm an aquarium. However, I obtained a length of rigid airline and some flexible airline, and went round at seawater change time bursting the algae. The seawater running down the tube to a bucket carried the spores with it. The algae was defeated - occasionally two or three appear but meet the same fate. No problem - very happy.

So! Explain the sigh. Yes, to date I am defeated. Well, not entirely to be truthful. I’ll mention the words Aiptasia and Manjano and there are so many aquarists who will no doubt say ‘Ah’ sympathetically. The dreadful anemones, weeds of the reef. They seem to grow so easily and often pick a spot that is really awkward. They don’t have intelligence do they?

I have never made the mistake of squashing them or scraping at them, this will only spread them around. I’ve considered the natural possible remedies - the Copperband butterfly (Chelmon rostratus) and the peppermint shrimp (Lysmata wurdemanni). I won’t try the Copperband for the reasons stated earlier, but I might try the shrimps. Reports on the internet, anecdotal not scientific, suggest that they could eat the anemones not that they will. It is quite likely that I’d get shrimps that turned their noses up at them.

So to date I’ve used Joe’s juice. This is successful and clearly destroys the anemone quite quickly. So how do the things keep re-appearing? When they do re-appear they are small, so they are new growths. Wandering around on the internet I found that apparently the anemones recognize the Joe’s Juice application as deadly. It is said that as they are attacked they release what could be termed ‘emergency’ spores - and hence new anemones appear. There is a new application available which apparently the anemones do not recognize as dangerous. Perhaps I’ll try that after a time so that effectiveness can be judged.

I said that I hadn’t been fully defeated by the anemones. There aren’t that many in the tank as periodically I attack them all when they are small - they are not allowed to grow (except one or two that have lodged in very difficult places, letting them grow a bit provides a bigger target). They don’t spoil the appearance of the reef at all. It’s just…well…they’re there and I know they are and they shouldn’t be! Why don’t they comply the little perishers.

A gardener doesn’t give up because there are weeds to be dealt with. There is no way I’ll allow the anemone to get too far under my skin. I tell myself they are part of nature; they’ll be on the reef. On the reef of course will be an efficient predator.

I enjoy my reef immensely and will continue to do so. The anemones are the only thing that I’ve not had success with. Sigh. But one day!

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Tags: aiptasia, Algae, aquarium-pests, marine-aquarium, reef-tank, sailors eyeball

Phew! What A Smell

Every time I sit and gaze at the aquarium, the gazing interlude is preceded by a visual glance at the main equipment - heaters, skimmer and the like. I also do this just before I feed, it only takes seconds and becomes second nature.

So there was I, defrosted brine shrimp ready for the fish, and my eye wandered around the aquarium equipment as usual. What attracted me to it I don’t know. I’d not noticed it earlier.

In the back bottom right hand corner it lurked. Dark and threatening and definitely not wanted. Some beast that had crept out of the rock?

No, much more simple than that. It was a patch of smear algae, sometimes called blue-green algae (which makes it sound quite pleasant, but it isn’t), also called Cyanobacteria.

This unpleasant stuff likes areas of low seawater flow, and sure enough it was in such an area. It also needs nutrients.

Out came the phosphate (PO4) and nitrate (NO3) tests. The tests showed ’undetectable’ for both. Perhaps there is a trace in the seawater but the tests aren’t sensitive enough?

Anyway, somewhat reassured, I removed the stuff with a stiff toothbrush. That’s about all that can be said for it, it isn’t particularly difficult to remove.

If there is any nutrient, why is it not being controlled? The skimmer operates as usual. All pumps etc are fine.

Then I noticed. I’m not sure if this is the reason, and if it is it seems a little illogical.

The drip rate from the output of the sulphur denitrator was exceedingly slow. One drip every few minutes! How could I have not noticed!

Anyway, I decided to clean the denitrator and ensure it functioned properly. I remembered the ‘nil’ reading from the nitrate test, but this must be because of the live rock. The pump was stopped and all feed/exit pipes disconnected. The tube containing the sulphur beads was taken into the kitchen.

I took off the sealing plate at the top of the tube and started to pour out the seawater. Wow! The smell was incredibly horrible, like rotten eggs that weren’t satisfied with being rotten and so double rotted. Yuk.

With this lovely un-aromatic stench around my head I emptied the tube and cleaned everything. All windows and doors were opened (good job it was a sunny day) causing my wife to come in, attracted (no, that’s got to be the wrong word) by the smell. An explanation was given, and she didn’t hang about but went back to the sweet air of the garden. The smell hung around the house for ages, even though fresh air had been given entry.

The problem, of course, was hydrogen sulfide, which gives itself away by the very distinctive rotten egg smell. The flow of seawater through the denitrator had been so low that the hydrogen sulfide had the opportunity to develop.

The denitrator was set up again, and I was about to switch it on and begin the process to re-establish the bacteria. Then I stopped and closed the flow taps.

There wasn’t a reading of nitrate on the test. The rocks in the aquarium are live. So why use the denitrator? The live rock must be doing its job.

I’ll have to monitor for nitrate regularly for a while, just in case the denitrator had taken any load off the live rock - perhaps the live rock will need to get up to speed.

So why is there a denitrator present anyway?

The answer is that when the aquarium was started 5½ years ago, the rocks that I used weren’t live. They were inert and highly porous, and over a long period they have developed into live rock - the holes, crannies and surfaces becoming the home of many tiny marine creatures, including of course bacteria.

So despite the fact that I have an inbuilt routine when feeding livestock or admiring the reef, perhaps the routine had become too rigid.

Lesson learned - I’ll not be caught a second time. I hope.

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Tags: Algae, aquarium, Aquarium Maintenance, Care, Water Quality, water tests

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