Enough Light? Must Be

Watching a marine aquarium is a great pleasure and probably one of the major reasons why so many keep them. With a reef system sometimes a new arrival is seen to appear, or a species of coral that is already present appears somewhere else.

On a few occasions I’ve noticed arrivals that must have come in with coral rock, such as a very dark and tiny crab that was very timid and only appeared at ‘dusk’. Its presence was shown by an exploratory claw appearing out of a crevice. The crab hasn’t been seen for a long time and no doubt has gone.

Corals too can appear when new live or coral rock is introduced. In this case the coral type is already present in the aquarium with a fairly large colony, and the new appearance is in a completely separate part of the aquarium.

As far as I can tell, the main colony is a Rhodactis species (the purchase was made years ago and the dealer didn’t have a clue). Rhodactis are also commonly known as hairy mushrooms and mushroom anemones. I think it could possibly be Rhodactis indosinensis – but is this correct as most grow larger than my specimens? Maybe they are Discosoma species. The colony is receiving plenty of light as it is half way up the reef (about half way up the aquarium depth). The new one, however, is not; it is right down at the bottom. The aquarium is 24″ deep (21.5″ from lights to coral). Further, this new growth is at the end of the aquarium and is partly shadowed by another coral.

Is my lighting system powerful? No is the answer, it’s a fluorescent array of five tubes, three marine whites and two marine blues (actinic). They’re not even T5’s, they’re T8’s. The reef is furnished with soft corals and they are perfectly happy but I had to wonder at the growth of this new one. The blues will penetrate well but even so….

The original colony is in an ideal spot apart from seawater flow which is a bit too vigorous, they prefer weak flow. However, I’ve left things as they are as the mushrooms are clearly healthy and open well, though not to as large an extent as with lower seawater flow.

The new one is the reverse; it’s in an area of slow flow. However, as said, I wondered about the light. It has been slowly growing for about 8 months now and has reached a size of 3″ across, which, because of the slow seawater flow, is full expansion. However, though I believed the slow growth must be because of light, or at least the lack of it, it seems this could be wrong. Looking at one of the references available to me * it seems that though light is no doubt an influencing factor it isn’t that important, as strong lighting is not required by Rhodactis species though they will tolerate it. Discosoma species prefer in many cases reduced light.

How did the new growth appear? It is possible it’s by natural detachment, but in this case is more likely to be my error. From time to time I have to get out the trusty and sharp scissors and reduce the colony to prevent interference with other species. Part of this is catching the detached parts. These corals are easy to ‘frag’ so if a small part escaped my attention and lodged it is more than likely to grow.

So there we are – what started as a general belief followed up by some simple research has turned my notion upside down. Goes to show how important basic research is. As far as identifying the species, I’d need a marine biologist and I bet there’d be uncertainty even then.

(*Reference: Aquarium Corals. Eric H. Borneman)

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Remember The Lighting

What is the most important part of a marine system? Lighting? Well no, it isn’t, seawater quality is the number one with both fish only and reef aquariums.

High seawater quality means there shouldn’t be any indication of ammonia or nitrite. Nitrate should be as low as possible (the guideline for a reef system is less than 10 ppm (parts per million) and for a fish only less than 30 ppm. Phosphate should preferably be undetectable. pH should be stable in the region 8.1 to 8.4. SG (specific gravity) for a fish only should be stable within the range 1.022 to 1.025, and in a reef system 1.024 to 1.025 (there are variations with SG which more advanced aquarists use for specific purposes). With a reef system there are more seawater parameters that could be monitored but those given are the basic ones.

So what has seawater quality got to do with lighting, this text is about lighting according to the title.

There are occasions when an aquarist is completely at a loss to explain why the corals are not as they were, with reduced growth and less expansion. Tests have been carried out on the seawater and it is top notch. What could be the problem? Perhaps a disease that is hard to spot? In fact it could be the lighting. Great care is taken when setting up a reef system to ensure the lighting is suitable and the corals, hard or soft, will confirm this.

With a fish only aquarium the lighting is not of such great importance. Its function is to permit the fish to see and the aquarist to see the fish. In addition, if the lighting, which is usually fluorescent tubes, is chosen with care the fish colours can be enhanced. Some colours react really well to ‘marine white’ tubes, and likewise to blue (actinic) ones. There isn’t any reason why more than two tubes cannot be used, but at least two should be in use, say one ‘marine white’ and one blue (actinic). Doing this not only assists with fish colouration, it permits the aquarist to create a ‘dawn/dusk’ sequence. Using electric timers, the blue tube comes on first, then half an hour later the white. At the end of the day the white goes off followed by the blue. This avoids washing the aquarium with sudden light and plunging it into instant darkness, both bad practices.

The reef aquarium is a different story. With these systems lighting is a close second to seawater quality. Most of the corals commonly kept have zooxanthellae in their flesh. Zooxanthellae are single celled algae and the coral gets its colour from them. In addition the corals obtain food as ‘rent’ from the algae; authorities have quoted the level of food supply as 80% or more. Algae, as other plants, require light in order to photosynthesize. The light needs to have sufficient power to penetrate the seawater to the depth of the corals and reach the algae. Power is measured in watts (W). If power is insufficient then the algae will get too little, this is why different power requirements are quoted for aquariums with different depths. In addition, the spectrum needs to be suitable. Light is measured in Kelvin, otherwise known as the colour temperature. Though there is more than one colour suitable for photosynthesis with some corals, blue is the one commonly used by aquarists. Blue penetrates deeply into the seas and oceans. Generally all light types use the Kelvin scale. If metal halide lighting is in use, the bulb(s) commonly used are 10000K and 14000K. The higher the number, the more cold or blue the light appears. Many aquarists use blue (actinic) fluorescent tubes alongside their metal halides. Many commercially produced metal halide arrays incorporate these tubes.

With reef lighting it is also advantageous to have a ‘dawn/dusk’ sequence. Whether the main white lights are fluorescent or metal halide, having blue tubes allows the sequence to be arranged.

So corals, or rather the zooxanthellae in their flesh, need lights that have a suitable colour and in addition the lights need to have enough power to penetrate the seawater.

Provided the aquarist has chosen the correct lighting system in the first place and other requirements are as they should be, the reef display should be lovely. This continues for longer than a year or more when eventually the aquarist notes that the corals aren’t as they were, as said earlier. There appears to be a slow reduction in extension. Perhaps there is a slight and maybe continuing change in colour. Again as said, the aquarist gets out his/her array of test kits but nothing appears wrong, the seawater is still of high quality. How about the lights?

With a fish only system there doesn’t need to be too much concern about the lights. As said they are normally fluorescent tubes and need changing when there is clear discolouration or blackening at the end of the tubes. It is not long after this point has been reached that the tubes are likely to start flickering or fail.

With a reef system the lighting needs more careful monitoring. To the aquarist’s eye there seems to have been no change to the light, as the tubes and/or bulbs switch on normally and they seem just as bright. This is not so however. As time passes the tubes and/or bulbs start to reduce in power which means that, given time, less light will reach the zooxanthellae. In addition, over time the spectrum shifts slowly and the painstakingly chosen lights emit a changed colour, again something the corals will not appreciate.

The best way that a reef aquarist can proceed is to keep a notebook; it only needs to be a small one. In it can go all sorts of memory joggers – including when the lights were first turned on. The manufacturers usually suggest in their documentation how long the lights should maintain their original specifications. There is considerable discussion within the hobby about light reduction/change periods, some suggesting that lights should be changed every three months. I have no facts or scientific reports to argue with, but I feel that period is definitely safe but rather short. Changing the lights no later than one year seems to be a reasonable general guideline. My reef is lit by a fluorescent array, and I change every nine months and have not had any problems.

The aquarist carries out many maintenance activities, a number of which are quite rightly concerned with seawater. There are the test kits that need to come out of the cupboard regularly, the routine seawater changes that partially replace lost trace elements and dilute the sometimes troublesome nitrate. Then there’s cleaning that very useful device the protein skimmer and ensuring that seawater flow is optimal. Plus the rest.

The lights are just there. They may get an occasional wipe with a damp rag but that’s usually all. They’re very dependable and all that is needed is a bulb/tube change after a specific time lapse. This will keep the corals happy if other parameters are good.

Happy corals mean a happy aquarist.

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The Long One

Like the majority of aquarists I have a schedule for maintaining my aquarium. With the commitments I have and the time available I’ve found that this schedule saves time – usually.

Saving time doesn’t always occur, sometimes, and it is infrequent, something occurs which takes up a lot more time. Not today though, all went well mainly.

My schedule depends on a number. Number one is clean the glass. Wow, that’s it! Number two is the same as one plus the intake filters on some powerheads, plus a routine seawater change. Number three is the same as one. Number four is a comprehensive clean. Included with all of these numbers is a check for any unwanted organisms such as Aiptasia. So as can be seen maintenance covers a four week cycle.

Maintenance is nearly always done on a Sunday as there is time available, in the morning anyway.  It all sounds a bit military maybe, but it works.

The number for today is four, the long one. New seawater ready and waiting, cleaning equipment near the aquarium. The aquarium is surrounded by carpet, so polythene covers are in place. They catch the drips and minor splashes very well.

The very first thing is to clean, with a hard toothbrush, my miniscule algae scrubber. This developed by itself and is obviously doing something as it exists! There must be some level of nutrients in the seawater feeding it. The photo shows it – I did say it is tiny, about 3 inches across and 2 inches deep! The seawater flow is from the hang-on skimmer.

Next the bracing struts and viewing glasses are cleaned with an algae magnet. Only the front and one end viewing glass are done, encrusting algae is permitted to grow on the others.

Exciting stuff this isn’t it! Now the four powerheads which sit in a small compartment are checked. The powerheads driving the under-reef spray bar and anti-phosphate filter have sponge intake filters and these need thorough attention. The anti-phosphate filter is shown in the photo; it is a homemade hang-on type. (Taking the photo was difficult, it is under an open stairway and space is restricted.) The other is an anti-nitrate filter, again homemade but this isn’t in use.

This maintenance is progressing well. The Eheim canister filter is next, the mechanical media has to be checked. This is comprised of fine and medium sponges and it can be surprising how much they catch from what appears to be clean seawater. I have to save numerous very small shrimps as well; these are placed in the display aquarium ensuring the fish don’t get them. There are numbers on the filters – this is from when they were both used for biological purposes so that they could be selected for cleaning, this doesn’t apply now as the biological media has been removed.

Getting there now and it is usually at this point that a cup of coffee appears. Thanks!

Siphoning is next on the agenda but before the main siphon tube is used, I attack any unwanted organisms. Today I located a few Aiptasia and these were dealt with. I’ll have to deal with more as time passes; they are never eliminated, probably because there are so many nooks and crannies in a reef aquarium. As long as they are not left to their own devices for too long they aren’t a problem.

So out come gallons of seawater with the siphon tube, this seawater will be dumped. (I used to use it for brine shrimp production but no longer do so.) At this time any debris spotted on the base of the aquarium is removed. There isn’t much base to be seen but it is checked anyway.

The new seawater is placed on the stairs above the aquarium and my wife kindly makes sure the tube doesn’t come out (not the siphon tube, one that is considerably longer). In goes the seawater.

Not quite done. I manually add certain additives to the seawater, these being calcium, bicarbonate and carbonate powder (for alkalinity) and iodine. Calcium is maintained at around 420ppm and alkalinity at around 4.0meq/L. I don’t measure the iodine level as it is only added once every two weeks at the minimum dose, there has never been a problem.

Nearly time to pack up now, just give the glass bracing struts a clean with a paper towel, likewise the viewing glasses. A check with the hydrometer is required, this is fine at 1024.

Final job – give the fluorescent tubes a wipe. Now it’s all done.

No, not quite. The two fish get some brine shrimp for being so patient!

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Cool It

The most popular lighting for reef aquariums, or to be more specific SPS reef aquariums, continues to be metal halide. This is because metal halides emit a very intense light that has considerable seawater penetration strength as far as aquariums are concerned. Metal halide bulbs are also available in the Kelvin range desired by reef aquarists.

There are two major disadvantages to metal halide lighting systems, the first is cost as they are electricity hungry. The second is heat emission which could be a problem in itself or cause a minor problem to become a major one.

With air temperature warming up for the summer the heat emission from the metal halide bulb(s) doesn’t alter, but the increased air temperature does mean that the aquarium seawater will naturally warm up. This in itself isn’t a bad thing as the heaters will not activate as much saving the aquarist money. Unfortunately, heat output from the lighting can increase the seawater temperature even more, moving it passed the design level. The heaters will of course not activate but these high temperatures are detrimental to the aquarium, for a start it upsets the stability of the system. Increased seawater temperature also reduces the amount of oxygen the seawater can hold, so in say a heavily stocked fish only aquarium there could be trouble. If temperature climbed excessively trouble could occur in any aquarium system. The bacteria housed within the bio-filter that are dealing with the toxins in the seawater are also consuming oxygen which could exacerbate the situation.

So overall it is undesirable for the seawater temperature to climb excessively. There are ways of cooling things down though and with metal halide this is a need that is more likely to be encountered.

Some aquarists counter the effect of the metal halides by cooling down the seawater itself. They do this by employing a chiller (a cooler) which must be specifically designed for marine use because of the very corrosive action of seawater. The chiller needs to be sized correctly or it could be ineffective, a check needs to be made to ensure the device is able to deal with the gallons of seawater involved and also the temperature reduction required – as far as the latter is concerned, if the chiller is matched to the gallonage it should be adequate as there is a temperature adjustment range.

There’s nothing really wrong with using a chiller as described. However, if the sole use of a chiller is because of the heating effect of the lighting it is not really economical. The lighting is consuming electricity which cannot be avoided (except to ensure the bulbs are correctly sized and the lighting on period is not excessive). A chiller is quite an expensive piece of equipment and quite expensive to run. If the seawater heats up anyway quite apart from the lighting fair enough.

If it is mainly the lighting that is causing the seawater temperature problem it is better to tackle the problem at source. Some free hanging metal halide canopies have fans built in which help direct the heat away from the seawater. The biggest problem is likely to be found with those lighting systems that are enclosed within a hood which sits directly on top of the aquarium. These canopies are often an ‘all in one’ build with the canopies matching the aquarium stand.

If the canopy is as described it could have been supplied commercially or been a DIY project. Commercial ones sometimes have fans built in, but not always. Some have air vents at the top and that’s it. These air vents do release heat as warm air rises, but the heat release is too slow and doesn’t deal directly with heat into the seawater. Fans are reasonably easy to install.

There are two ways of installing the fans; the first is to have two fans, one at each end, with an air vent in the middle at the back, and the second is again to have two fans but no air intake at all. In the second version an air vent could be fitted either in the middle or above, it will not do any harm. The idea is to direct a cool air flow across the space between the metal halides and the seawater surface.

Metal halide canopies are of necessity quite large with a good space above the seawater surface, so there should be plenty of room to fit a fan at each end. Some aquarists use computer type fans but the danger with these is that they may not move enough air to deal with the heat. A better option is to use mains electricity powered fans. The ones that are useful are those smaller units that are fitted into bathrooms as extractors; they are usually a small plastic box with vents each side and the fan already mounted inside. Some of these type fans are reversible, that is the fan direction and therefore the air flow can be reversed. If two of these fans are obtained one can be fitted at each end of the lighting canopy. Two holes will obviously need to be cut but if the edges are a little ragged the fan units could fit on the outside to cover them up, the units need to be checked for this option. Some units have a removable outside cover which also fastens the main unit on the inside securely.

In the first option the fans are fitted and there is an air vent in the middle of the canopy back plate. The fans are set so that they both suck in cool air from outside the canopy. This causes an increase of air pressure – not a lot – inside the canopy and the air escapes through the air vent taking heat with it. Care has to be taken that the air doesn’t escape downwards towards the seawater or the cooling effect could be partially or wholly lost.

The second method, with or without an air vent, is probably the best. The fans are fitted at each end of the canopy but this time one fan, it doesn’t matter which end it is at, is set to suck air in. The opposite fan is set to blow air out. This means that there is a powered cooling air flow through the lighting canopy. If there is an air vent some air could escape, but again heat will go with it.

The paragraphs above are concerned mainly with metal halide lighting, but those aquarists who have fluorescent lighting such as T5’s or earlier types could be surprised at how much heat actually builds up in the canopy. A fan cooling system could be an advantage.

There is a major point that needs to be mentioned and this is concerned with safety. Electricity incorrectly used is dangerous. The fans need to be securely fitted and not subject to splashing. Wiring to the fans needs to be completed safely, with the wires going to correctly fused power outlets, and the wiring obviously needs to be properly secured, not trailing. Any doubt and advice from someone competent should be obtained.

Preventing the lighting system from overheating seawater is generally simple and can be done in a way which minimizes the additional electricity demand.

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If Seawater Tests Are Fine But…

We are often going on about the quality of seawater and we believe quite rightly so. Seawater quality is the number one priority, no matter what type of aquarium it could be, fish only, coral only, or mixed reef.

Of course, even if seawater quality is correct there could still be problems. Fish need to receive the correct nutrition, and there needs to be a general lack of stress. There are more. However, as said, seawater quality is the number one and regular tests should be made.

Though it doesn’t affect a fish only aquarium anywhere near as much, lighting is number two on the list. This applies to a reef system whether corals only or mixed. This high priority for lighting is because of the needs of the corals. Within most corals are zooxanthallae, single celled algae which are essential to the corals’ wellbeing.

So there’s a problem with the corals? Seawater tests indicate nothing wrong? What could it be?

The link is to a text supplied by aquaristsonline.com which could be of interest in the above context.

http://www.thereeftank.com/blog/look-after-the-lighting/

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What Are Moonlights For An Aquarium?

For a marine fish only aquarium lighting is simple, the fish need to be able to see and be seen. For a reef system the lighting is more complicated, as not only do the fish need to see and be seen the corals will normally have zooxanthallae within their flesh and this single celled algae needs to flourish so that the coral does too.

There’s a form of lighting that presents not a single headache and that is moonlight.

In the wild as everywhere else there is day and night, plus the transitional periods dawn and dusk. At night there is often moonlight which is missing from most aquariums.

Having moonlight is not essential. Corals are not going to suffer from the lack of it. Having mentioned corals and moonlight, isn’t it fascinating the mass spawning of corals on a reef, all of them triggered more or less at once.

Moonlight is optional. For those well-heeled aquarists with LED (light emitting diode) arrays it is possible that it is built in and ‘on’ times can be programmed. For most of us it is an extra purchase.

When all the lighting is off except for moonlights the effect on the captive reef is lovely. Weak shafts of light descend onto the corals, flickering across them. It can make the night period quite beautiful and draw the aquarist to have a look at a time when usually he/she wouldn’t.

Moonlights are a small array of blue LED lights. Usually they are supplied in a small unit, with perhaps five or less LED’s. There are larger units. Sometimes they are powered by a plug-in transformer style electricity supply. Their demand for electricity is very low, so very little will be added to the electricity bill.

As said, putting moonlights onto an aquarium is optional as there isn’t a technical requirement. Very advanced aquarists could well experiment with them to see if corals could be induced to spawn though this would be difficult and time consuming. Most of us would use them purely for the lovely effect, and expand the period when the aquarium acts like a magnet.

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Watch The Heat From That Metal Halide

Metal halide lighting is very popular with reef keepers, particularly those who keep hard (SPS) corals. This is because it is a very powerful light that can penetrate deep into the aquarium provided that the bulb wattage has been correctly selected. Metal halide is likely to be superceded before too long by LED arrays, but at the moment metal halide is the most popular for the reef.

Even though metal halide is so good at lighting reefs there are disadvantages. There are two major ones, the first being that metal halides are electricity hungry and will add significantly to the aquarium energy cost. The second is that they generate a lot of heat. It is this second disadvantage that is being considered.

The lighting has to be hung well above the seawater level and this is because should the protective glass or bulb be splashed it could crack as it is so hot. It needs to be remembered that if the glass is to be wiped over with a damp cloth it needs to cool down first.

We nearly all like sitting in a favourite spot in the sun, feeling the warmth. Metal halides bulbs are a little like the sun in that they radiate considerable heat and unfortunately this could cause trouble. Many reef keepers use cooling apparatus to keep the temperature of the seawater under control though this for most is only in summer. This apparatus could be fans in the lighting hood, a pedestal fan alongside the aquarium, a ‘chiller’ (electric seawater cooler), or perhaps a combination. Stability of seawater parameters is important and this includes temperature. If the temperature climbs too high livestock welfare is in jeopardy. If the temperature is noted to be climbing much too high then the first action is to turn off the metal halides until cooling equipment can be used. The aquarium shouldn’t be plunged suddenly into total gloom, so the blue (actinic) fluorescents can be left on.

There is another danger from metal halide heat as well, and I wasn’t aware of this until recently. There are aquarists who use acrylic aquariums and these aquariums, like glass ones, have stress bars built in across the top. It is reported that the major failure with acrylic aquariums is where a metal halide bulb is directly above a stress bar. The heat softens the acrylic which then stretches under the outward pressure of the seawater and splits or worse could occur.

So if it is possible to move the bulb away from the stress bar this should be done. If the metal halide is then off centre this could be all right, check the light coverage. The guideline is that a metal halide bulb at the correct height above the aquarium should light three feet of aquarium length.

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