The Basic Kit For A Marine Aquarium Part Two – Reef

Part one dealt with a fish only aquarium and much of what is said in that text also applies to a reef system. The text therefore repeats itself in several places.

However, the reef aquarium has demands that are additional to the requirements of a fish only aquarium. This is not to say that a successful reef aquarium is much more difficult to obtain, it isn’t. However, the aquarist must pay attention to the additional needs. The reef aquarium demands are different, not difficult.

Despite the number of modern books available and information on the internet confusion continues to arise with a newcomer. This confusion is sometimes caused by the book and/or the internet. Books could be out of date as far as equipment is concerned, and an internet forum could cause confusion by the different opinions expressed.

Another area of confusion and often ‘overspend’ is the LFS (local fish shop). Some are very good and will ascertain the level of experience of the aquarist, and what he/she is aiming for. However, there are those that don’t and these are the ones that cause trouble. The LFS, good or poor as far as the beginner is concerned, is there to make money. If they don’t make money they won’t be there much longer. So the beginner is told they must have this, they must have that, this will be all right, that should do. Unfortunately this all adds up to a fair amount of money and ‘should do’ actually is not good enough.

The Aquarium. (The glass or acrylic box it all goes in.)

First of all (having obtained the agreement of the wife/husband/partner – let’s play safe) a check of available space should be made. The position of the aquarium must be close to an electrical outlet and the outlet must be accessible when the aquarium is in position, it can be just to one side or just behind (not in the middle). Also and important, check the strength of the floor to ensure it is strong enough. Concrete floors are fine and so are most suspended floors, but nevertheless check. An aquarium full of seawater and rocks is very heavy.

Once the available space is known then this is not necessarily the size of the aquarium that will be obtained. It is necessary to consider the overall cost and future running costs before making the commitment.

The Lights. (So fish can see and be seen – but there is more.)

Lighting for the reef aquarium is an area where confusion understandably could arise. Basically it is simple as will be seen.

Reef aquariums house corals. These could be of the soft or hard varieties, and there is one thing they have in common. Most of the corals kept in home aquariums contain zooxanthellae. Zooxanthellae are simply single celled algae which are embedded in the flesh of the corals. The alga is very important to the corals as 80% or more of the corals nutritional needs are provided by it. It is the alga that gives the coral its colour.

Algae have a particular need in order to thrive and that is light. Light permits it to photosynthesize, with insufficient light the algae will suffer and so will the coral. So the aquarist has to provide adequate lighting.

Adequate lighting will have two properties: the first is spectrum and the second is power. Spectrum simply means, as far as we are concerned, colour. Zooxanthellae respond well to blue light and manufacturers produce bulbs and tubes that will reproduce this. The light is in a fairly restricted range and is referred to as ‘actinic’. (Using these lights has the secondary benefit of causing some corals to look really amazing.) In addition to blue lighting, a cool white light is used often referred to as ‘marine white’. This is a mixture of colours, including blue, but to our eyes it appears white. So reef aquariums usually employ a mixture of light sources as described.

Light is measured on the Kelvin (K) scale. Light could be 10000K, 14000K up to about 20000K. The higher the number the more blue, or cold, the light appears. A reasonable metal halide bulb to use with a reef system would be 10000K or 14000K. When used with fluorescent blue (actinic) tubes a good effect is achieved.

The light of course has to reach the zooxanthellae to be of any use, and it has to get there with sufficient brightness. Light is rapidly weakened by seawater. The colours disappear individually; the first to go is red in the first few feet though blue penetrates very deeply. What this means for the aquarist is that the lighting over the aquarium has to have sufficient power to penetrate the seawater sufficiently. This power is measured in watts (W) and manufacturers provide lighting of different power outputs.

There are two main lighting types with a third becoming likely to supercede the first. The first is metal halide bulbs. The second is fluorescent tubes. The third is LED lighting. It is not intended to go through them all technically but a basic description follows.

Metal halide bulbs are currently used a great deal on reef aquariums. As stated they are bulbs which are housed in a reflective canopy. They produce a pinpoint and very bright light. The bulbs can be obtained in various spectrum and power variations. Unfortunately there are disadvantages in their use: they are expensive to run, in other words they are electricity hungry, the bulbs need replacing periodically, and they are capable of heating up the seawater. Though there is some argument over the necessity, many aquarists use metal halide bulbs together with two fluorescent blue (actinic) tubes.

Fluorescent tubes have been around for a long time. There is a choice in their length so various size aquariums can be accommodated. Manufacturers produce different spectrum outputs so that a mix can be used if desired. If they are to be used they should be fitted with reflectors. Using the colours described earlier, a mix of blue (actinic) and marine white is desirable. As many tubes fitted with reflectors as will fit should be used. If an even number of tubes will fit, have half blue and half white intermixed. If the number fitted is odd, the odd one should be white. T5 tubes are recommended, these are driven by electronic ballasts. The disadvantages of fluorescent tubes are that they must be changed periodically and they do not have as much penetrative power as metal halide bulbs.

LED lighting is becoming more available and the combined output of the LED’s is suitable for a reef. The lighting can be obtained as a canopy array containing many LED’s or as tubes containing much fewer LED’s. The latter are available with different colour outputs, the most useful probably being blue and white. If using the LED ‘tubes’ it is best to fit as many as possible over the aquarium, again with a mixture of blue and white as described above. The canopy array is a large over-tank light source containing many blue and white LED’s. There isn’t a requirement for any additional lighting. It is important to have an array large enough to light the full aquarium, as far as possible. The advantages with LED lights are that the lights last for years without the need for replacement, they do not heat the seawater, they can sometimes be controlled often by built in timers, and they are reasonably cheap to run. The disadvantage, at least at the moment, is that they are expensive.

So how is a lighting system chosen? No-one wants to over-light their aquarium as money will be wasted on electricity. Nevertheless, as said, the lighting must be adequate. Spectrum is quite easy to decide, all corals that require light will benefit from the same spectrum – blue and white.

Power is the problem usually. Power is measured in watts (W) and there is an array of power outputs never mind lighting types.

The first thing to consider is what corals are going to be kept, soft or hard? Most home aquariums are not deeper than 2 ft and it is the depth that is important.

If soft corals are to be kept, then fitting T5 fluorescent tubes as described should be adequate. Consider LED’s but as said they are expensive. Metal halide bulbs will probably be overkill.

If hard corals (SPS, which stands for short polyp stony) are to be kept, then again T5 fluorescent tubes could be adequate. (Note the change from ‘should’ to ‘could’.) Observation of the corals will be required to ensure they indicate growth and health – those at the top areas of the reef should be fine, it is the ones lower down that could be receiving less light. Consider an LED canopy array, but as said they are expensive. It could be desirable to ensure adequate lighting by employing metal halide bulbs along with two blue (actinic) fluorescent tubes in reflectors. The guideline for metal halide bulbs is that one bulb will light three feet of aquarium. So a six foot aquarium would need two bulbs.

Now for power on which light penetration into seawater depends. The guidelines for metal halide bulbs are: for a 24″ deep aquarium 400W, for an 18″ deep aquarium 250W, and for a 12″ deep aquarium 150W. (Note – 1″ is circa 2.5cm.)

The guidelines given are to enable proper light penetration generally to the bottom of the aquarium. So position of corals on the reef will dictate to a great extent the bulb power required. If the aquarium is 24″ deep and the hard corals are in the top 12″ then a 400W bulb could be downsized, subject to what is to be kept in the lower part of the aquarium.

It is a good idea when setting up lighting to include two electric timers, as they can be used to provide a more natural ‘dawn and dusk’ effect. The blue lights come on first, then half an hour later the main lights, be they metal halide or white fluorescent tubes. At the end of the day the white lights go off, followed half an hour later by the blue lights. The need for electric controllers may not apply to LED systems as sometimes these are included.

The Bio-Filter. (The bacteria factory providing life support.)

The bio-filter (biological filter) is absolutely essential. If one is not present, or is inadequate, the livestock will suffer or die.

There are two ways of providing bio-filtration (there are more than two but two will be looked at). These are first live rock and second canister filters. It is necessary to roughly know the total gallonage of the aquarium. The gallonage is easily calculated by using the formula Length x Breadth x Height, the answer divided by 231 equals US gallons. Allow for a 1″ airspace at the top of the aquarium and 2″ at the bottom for a decorative sand bed.

Live rock is a natural product which is bought ‘cured’ from a LFS. ‘Cured’ means that any potential die-off of organisms has occurred and the rock is ready for introduction to the aquarium. The rock contains bacteria that deal with the production of toxic substances in the seawater; this process is called The Nitrogen Cycle. The usual guideline for the amount of live rock is 1½ lbs per gallon of seawater. This guideline suffers from the fact that different live rock has different weights, so the supplier should advise the necessary amount required for the type being sold.

The live rock also acts as a natural décor for the aquarium interior.

A canister filter is a man-made device where seawater moves through a cylinder filled with bio-media. In and on the bio-media are the bacteria, once the bacterial culture has been established. The seawater flow is powered by an electric motor. These devices are fully capable of maintaining a bio-filter. A check should be made that the device is capable of handling the gallonage of the aquarium; the manufacturer’s information should provide this.

Of the two bio-filtration methods live rock is the one recommended particularly for a reef system. The live rock in addition to its filtration capabilities provides the material for a natural looking reef, and hopefully some wild life that has survived the curing process could appear. Another reason for using live rock is that within reason it can deal with nitrate. With a canister filter the Nitrogen Cycle stops after the production of nitrate. This does not mean that canister filters cannot be used as nitrate is controlled easily enough.

If a canister filter is to be used then the aquarist will need to purchase decorative rock to aquascape the aquarium. This will not be live rock of course but dead inert rock. ‘Inert’ means that the rock is known to be totally safe in seawater; nothing will leach out that is detrimental. There isn’t any control on the amount of inert rock used; it is up to the aquarist to create the aquascape desired. However, if fish are to be kept (they need to be reef safe) then consideration needs to be given to swimming space. Some fish need more space than others.

Powerheads. (These provide seawater movement.)

Seawater movement in an aquarium is required so that oxygen can be replenished and the general environment remains healthy. In addition, the movement helps corals rid themselves of mucus and detritus and brings food to them. Though there are several ways to provide seawater movement, powerheads are much used and fully acceptable. Here we deal with basic narrow outlet types, though there are wide outlet types available. Properly situated, narrow outlet powerheads are acceptable.

Usually at least two powerheads are used as this permits chaotic and random seawater flow to be created. One powerhead could go in one rear corner of the aquarium and the second in the other. The outlets, which generate linear flow, are directed at more or less the same place on the front glass. This means that the two flows interfere with each other as well as ‘bounce’ off the front glass and many swirls and multi-directional flows are created. It is usually necessary to experiment a little with the best positions for the powerheads, but it isn’t difficult. The movement of corals or bits of detritus in the seawater indicates the flow patterns. The outlet from the powerheads must be positioned so that strong linear flow from them does not strike a coral.

The guideline for seawater movement in a reef system depends on what is being kept. If it is a soft coral reef then the seawater gallonage in the aquarium should be moved around 10 times per hour. If the corals to be kept are hard (SPS) types then the seawater should move around 20+ times per hour. Note that these are guidelines and not rules – it is not critical, the volume moved does not have to be completely accurate.

For example using the guidelines, in a 50 gallon aquarium containing soft corals the total seawater movement per hour required is 500. Therefore each powerhead would need to move 250 gallons per hour. In an SPS system, the total seawater movement required is 1000 gallons, so each powerhead would need to move 500 gallons per hour. There isn’t any requirement to have two powerheads, many aquarists use three, four or more depending on the size of the aquarium and the amount of seawater that has to be moved. The required power of the powerheads is achieved by dividing the number of powerheads into the amount of seawater that needs moving. The seawater currents created should be as described.

Decorative Sand Bed. (It looks good.)

There isn’t a need for a decorative sand bed. It hasn’t a function except to make the aquarium look more natural and cover up the bare glass bottom. Decorative sand at the base of a reef does look attractive.

If a decorative sand bed is incorporated, then there are things to consider. First, it should be constructed of coarse coral sand, as hopefully this will not move around too much in the seawater currents and dirt will not penetrate too deeply too quickly. It is likely the sand will move and hopefully it will end up in decorative swirls and ripples similar to sand on a beach adding to the attraction. Second, rocks whether they are the live or inert variety should not rest on the sand. This should avoid rock falls and sand compression. So the rocks are in first then the sand. Last, the sand should be 1″ to 2″ deep. This depth will assist with cleaning by stirring when it becomes necessary to keep the bed looking its best.

The Protein Skimmer. (Not last and not least.)

After the bio-filter the protein skimmer is, perhaps arguably, the most necessary device. The protein skimmer is a great aid to the maintenance of high quality seawater. In an aquarium organic substances are produced which are generally termed Dissolved Organic Matter (DOM). This is mainly undesirable.

The protein skimmer removes much of this DOM. All types of skimmer work on the same basis: seawater flows through a chamber where very high numbers of tiny air bubbles are present. The DOM is attracted to the air/water interface and ‘adheres’ to the bubbles. The bubbles rise and fall into a collection cup and periodically the collection cup is emptied.

Most skimmers used nowadays are electrically driven and employ a ‘venturi’ device to draw air in. There are two types, stand alone and hang-on. With the basic aquarium set-up, where a sump is not in use (a sump is an additional tank under the display aquarium), the hang-on type is most useful.

Manufacturers nowadays are perhaps more accurate in their claims for the performance of their products, but nevertheless the following guideline applies: obtain a skimmer that is stated to be capable of handling around twice the gallonage of the aquarium. It is unlikely that a skimmer will be obtained that is stated to handle the aquarium gallonage exactly, but one could be close, so at least choose the skimmer higher up the scale, not one lower down.

The skimmer is said to be the number one ‘poor buy’. This means that many aquarists setting up a system try to economise on this item, only to discover the inadequacy of the device and their mistake later, resulting in another purchase and unnecessary expense.

Heaters. (Got to keep the coral reef cosy!)

The corals and fish that are to be kept are from the warm seas of the wild reefs so it follows the aquarium seawater needs to be warm, between 75 and 80 deg F. Many aquarists choose 77 deg F.

The method of keeping the seawater warm is to use a device called a heater/stat. This is like a long fairly thin tube, the more powerful the heater the longer the tube. The heater is turned on and off by the ‘stat (thermostat).

It is best to have two heaters. Though they are quite reliable nowadays, failure is not unknown and it is often the ‘stat that is the trouble. It either sticks in the ‘on’ or ‘off’ position, usually the ‘on’. This means that the heater continues to apply heat even when the seawater is at or above the required temperature. If there was one heater it would heat the seawater excessively too quickly with dangerous consequences for the livestock. With two heater/stats this can be avoided to a considerable extent as each heater/stat is rated at half the power required. Therefore a safeguard is provided.

The guideline for selecting the heating requirement of the aquarium is: if the aquarium is in a heated room allow 2 watts per gallon of seawater. If the aquarium is in an unheated room allow 4 watts per gallon.

So, with 50 gallons of seawater and using two heater/stats, in a heated room the power requirement in watts (W) of each heater/stat will be 50 watts. In an unheated room the heater/stats would be rated at 100 watts apiece.

Calcium Provision. (Let the corals grow.)

Calcium is used by corals in their growth processes, mainly by hard corals that can make quite a demand, and also by soft corals which have ‘spicules’ (stiffeners) in their flesh. Other livestock such as snails and shrimps also have a need. So it follows that calcium must be present in sufficient quantity.

The guideline for calcium in a reef aquarium is 400+ ppm (parts per million). Incidentally, ppm is considered the same as mg/l. This amount is fine for soft coral aquariums though a higher level is better, say around 420 ppm. Aquarists who have a hard (SPS) reef often maintain higher levels than this, 450 or even 480 ppm.

So how is this calcium supplied? Routine seawater changes help but are not usually sufficient. It depends on the demand and the size of the aquarium. A small or medium soft coral reef could use supplements to provide calcium, and probably the same for a small SPS reef. The answer with these is to use a supplement and judge how much is being used and if it is effective and not too expensive. If it is ineffective or too expensive then the following could apply.

A medium to large well stocked hard coral (SPS) reef will make a considerable demand for calcium. It is unlikely that supplementation with a commercial product will be cost effective. Therefore a device for providing the calcium has to be used. There is more than one way of providing calcium but here the calcium reactor will be considered.

A calcium reactor is a device that passes seawater through a media filled chamber that has a low pH. The media is rich in calcium. The pH is lowered in the chamber by injecting controlled amounts of carbon dioxide. The media slowly dissolves and is passed into the aquarium. The device needs adjustment for seawater flow rate and for the injection speed of the carbon dioxide.

Once the aquarist is aware of the calcium demand of the corals then the reactor can be adjusted to meet it. New media is required from time to time.

As experience grows the aquarist could find supplementation other than calcium is also required, but calcium is the only one that will be looked at here.

Seawater Test Kits. (Seawater quality is so important.)

In order to keep a high quality marine environment it is very necessary to routinely test the seawater in addition to doing routine seawater changes. The test kits needed are easily obtainable, not excessively expensive and easy to use.

The first requirement is a hydrometer. This is usually a one-time buy as it is re-usable. The hydrometer is a device that indicates the specific gravity (SG) of the seawater. In a reef system the SG should be 1.024 or 1.025 and stable.

Next are the tests that look for undesirables in the seawater. The three of interest are ammonia (a deadly toxin), nitrite (a toxin nearly as deadly), and nitrate (which is nowhere near as bad but detrimental at too high a level). These kits carry out a finite number of tests and a new kit will be required.

Next a test kit for pH is needed. Seawater is alkaline and the pH test checks this. The reading should be between 8.0 and 8.4. Again the kit has a finite number of tests and a replacement will eventually be needed.

There is a saying that nothing should be put into the seawater that cannot be tested for. Well, calcium is being added and this needs to be checked. The levels required have already been discussed. This also is a kit that will need replacement in time.

There are other tests that could be made and the aquarist will learn of these as experience grows.

Dry Sea Salt. (Well, it is salty water!)

There are many different makes of dry sea salt available and this is a choice for the aquarist. The most salt will of course be used in the initial mix. Following that, routine seawater changes should be done weekly, and at least to start, 10% of the total gallonage should be changed.

A Reverse Osmosis Filter. (Makes good water.)

Though this is not an absolute necessity for the running of the basic aquarium, the advantages of using one means that it is highly recommended. This is because much tap water contains undesirables.

When tap water runs through a reverse osmosis (RO) filter, the usable fresh water that emerges is 95 to 98% pure. Any contaminants have been removed. The fresh water can be used with confidence with the dry sea salt.

The Cost. (Not the most exciting consideration.)

There are two costs to consider.

First, now that everything has been listed, that is, the aquarium and the necessary equipment, check prices at the LFS and on the internet. Note down those selected and add them up. The answer is the indicative cost of setting up the system.

Now list the electrical items. Find out the wattage (W) of each and write it down (the information should be on the packaging, the device, or the manufacturer’s information). Now add up the list of watts. This is the indicative total power requirement of the system.

However, not everything will be on all of the time, lights and heaters being an example. An allowance is made for these. To calculate the ongoing electrical cost, use the article on this site called ‘A New Aquarium – It’s Exciting But Check Running Costs’. The calculation is straightforward. Alternatively, use an online calculator; these are available on several marine forum sites.

If everything is acceptable, fine. If not, perhaps downsizing the aquarium would produce a positive outcome.

(Note : All of the above links are to the relevant category of Aqua Compare and open in a new window.)

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