It’s A Sunny Life

We marine aquarists are lucky in more than one way, and a part of this luck is that our aquariums are always sunny, no matter what Mother Nature has to say about it, wherever the aquarist may live.

Day in, day out on comes the lighting system and, surprise, the sun is shining and does so all the time until dusk when the actinics are on alone. Ok, there are some who have very advanced lighting systems (Led’s) which can simulate cloud cover but for most of us it’s a permanent clear sky.

Of course there are those aquarists who live permanently in a naturally sunny climate. There they are with a coral reef to dive on but then human nature being what it is they are not always completely happy.

A few years ago – cripes, as long as that! – my wife and I were in Barbados for a holiday and were in the process of hiring a car for sightseeing purposes. The garage proprietor was a friendly chatty type and the talk came round to reefs, I was asking which would be the best area for snorkeling. It turned out that he was a marine aquarist. How very widespread this hobby is! Sadly I never got to see his aquarium but he advised he obtained his fish (and corals?) from the reef. I mentioned I was surprised as he had a huge natural ‘aquarium’ to swim in, but he said it was wonderful to see the fish within his home.

When talking it turned out that what he really, really would like was a holiday such as we were having, two weeks or so away. ‘What – and you live in such a lovely sunny place’ was my response. He said he would love to take his family to England. England, very beautiful but well known for its cloudy days and rain.

It just goes to show that perspective depends on many things, one of them at least being what you haven’t got. So my ‘aquarists are lucky’ is probably down to the fact that there aren’t any coral reefs near me and the sun doesn’t always shine.

My soft coral reef continues to do really well. I do the required routine maintenance and spend time admiring the aquarium picture. I still have wars with those xxxxxx aiptasia anemones and have to admit that this is one area where I have not been successful, having failed to eliminate them. However, eliminating these aquatic weeds in a reef aquarium is just about impossible as there are so many nooks and crannies. I attack them periodically when they are small, the reason for doing it when they are small is that I understand (from reports on the internet) that aiptasia anemones are able to release ‘emergency spores’ when they are facing oblivion, as apparently they recognize they are under lethal attack. I don’t know if these reports are correct and scientifically supported. Anyway, if correct I assume small means a lower spore count. Periodic attacks also keep them well under control and prevents them spreading.

Now summer is well and truly with us I’ve tested my 12 inch electric fan, if temperatures raise unduly it will be used for cooling.

Talking about cooling, I’m sure there are a couple of beers in the ‘fridge….

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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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How Should I Go About Choosing A Heater For My Reef Tank?

Most marine systems are set up to house tropical livestock, which means that attention has to be given to maintaining a moderately high seawater temperature. The recommended temperature is 75 to 80 deg F, though some experienced aquarists run at a higher level to increase the metabolism of all the livestock. The novice should not do this but stick to the recommended levels.

Heating the seawater is straightforward nowadays, as a unit called a heater/stat is commonly available. These take the form of a longish tube with a thermostat at the top end and a heater unit at the lower end. They are available from local retailers and online and the price is very reasonable.

Aquarium heaters used to be the source of a few problems in the past with sticking contacts in the thermostats or general failure. Nowadays they are more reliable though the danger of a sticking thermostat is still present. There are ways of reducing the risk but obtaining the heater unit is the first consideration.

The heater/stat is available in several wattages (W) and the size of the aquarium, or rather the net total gallonage of the aquarium which includes any sump, dictates the heating need. The usual guideline is to allow 2 watts per gallon of seawater for a normally heated room. If the room is unheated then the wattage is doubled. So keeping things simple, a 50 gallon system in a heated room would require 100W, and in an unheated room 200W. These wattages are not based on a formula that must be rigidly followed, what is required is that the heating is known to be fully capable for all possible demands. Wattages that are a little higher – within reason – should not be harmful.

It may be thought that buying a bigger heater, say 400w in a heated room, would be better as that capacity will not face any problems ever. However, it is not a good idea. If the thermostat contact sticks in the ‘on’ position then the seawater will heat up more quickly, possibly meaning that the aquarist doesn’t notice the excessive temperature problem until it is too late.

Once the heating requirement is known there isn’t anything to stop the aquarist purchasing a heater/stat of the correct wattage (if the wattage doesn’t match the net gallonage the next heater up should be chosen). Again remembering that though modern heaters are much more reliable than they used to be potential problems have not been totally eliminated, so it is best to obtain two heater/stats. They should not individually equal the full heating requirement of the system, but half of it. In other words, if 200W is required then obtain two heater/stats at 100W each. This will help to prevent a problem with one of the thermostat contacts sticking ‘on’ or ‘off’: if one sticks in the ‘on’ position then the other will turn off when the design temperature has been reached slowing down the temperature climb, or if it sticks in the ‘off’ position then the other heater will prevent the seawater cooling too quickly. Hopefully the aquarist will notice the problem in the extra time the system affords.

With two heater/stats the temperature setting on each should be the same. Many heater/stats are set at 75 deg F before they leave the factory so if the aquarist requires a higher temperature then the devices will require adjustment. This brings up another point: when purchase is being considered ensure any temperature adjustment is easily accomplished. There are heater/stats nowadays that display the temperature setting on a clear scale and an easy to use adjustment knob is at the top of the unit.

There isn’t an absolute requirement that two heating units are used, but for the reasonable extra financial outlay it is worthwhile.

Finally, before parting with hard cash find out what the temperature variance of the heater/stat is. The temperature variance is the difference between when the heater turns off and when it turns on again – in other words the sensitivity of the thermostat. A variance of 1.5 deg F is good but manufacturer’s products vary.

Really that is all there is to consider when obtaining heater/stats, but I’ll just mention one other thing. I should point out that though this is generally desirable for accuracy and dependability there isn’t an absolute requirement.

Some aquarists when setting up a system decide to employ an exterior electronic controller. They can of course be retro-fitted. The controller usually takes the form of a small box perhaps 4″ square or so. There is a mains electricity connection, and a socket from which the electricity for the heaters is supplied. In addition, there is a small temperature probe that goes in the seawater. Temperature is set usually by means of a small knob, and the heaters are shown to be active or not by an indicator light. If two heater/stats are in use, they should both be connected to the controller (ensure the power handling capacity – wattage – that the controller can handle is not exceeded). Once the design temperature for the seawater has been set on the controller, the temperature setting on the heater/stats should be 2 deg F higher. This means that the heater stats are always in the ‘on’ position. Some electronic controllers pulse electricity through the heaters, reacting to the probe readings. If the seawater is trying to cool, the pulses are longer (so the heaters apply heat for longer), if it starting to warm up too much the pulses shorten. It is reported that as the heater coils are always warm, not going from cold to hot and back again the heating coils last longer. These electronic units could control temperature to +/- .5 deg F. It sounds as though they could be an expensive item, but they aren’t.

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The Cold Is Coming…..

It is that time of year again where the climate is starting to change to the colder type. It is not the type of weather I personally am a fan of. I like warm weather where time can be spent in the garden, have barbeques, play with the family etc but there is nothing we can do to influence the climate is there?

There are of course certain areas of the world where the climate is still quite nice but where I am from a chill can certainly be felt in the air. For the people who live in more temperate climates than I do then I can officially sayheat that I am very jealous – not that I am complaining about the area I live in as it s very nice but I do wish it could be a bit warmer.

Anyway now that the cold is coming we need to think about our aquariums and how we can keep the heat inside where it needs to be.

We can’t win can we – in the summer periods we concentrate on preventing them getting to hot and in the colder periods we concentrate on keeping them warm.

This does depend upon whereabouts the aquarium is located in the home but for the majority of aquarists heat loss is something which needs to be prevented if possible. If for example your aquarium is located in your family room then due to central heating the aquarium will be ok for the majority of the day, however what about night time when normally the central heating is turned off and we are all tucked up nice and warm in our beds.

Another example could be the in-wall aquarium where the front of the aquarium is like a living picture however the rear and sides of the aquarium are in another room. This could be a garage, fish room etc – somewhere where perhaps heating is not provided. In these areas it is going to get cold. This is what my aquarium setup is like.

The first things to check are your physical heaters. You need to ensure that the thermostat is not stuck at all and that the heaters are still working correctly. A good way to do this is to remove them from the aquarium – after unplugging them first and then put them in a container with some cold water in it. The thermostat should pick up the cold water temperature and turn the element on which will in turn heat the water. This means that the heater is working ok. Don’t remove the heater just yet. Let it heat up the water until it is the correct temperature and ensure that it turns off ok. If it does then the heater is working as expected. If it does not then the heater needs to be replaced.

A better way in my opinion is not to rely upon the thermostat of the actual heaters but to utilise a device which monitors the water via a probe and turns the heaters on if required. It is the same principle but I have had to many heater failures to put my complete trust in them. The controller I use (as does John) is one which monitors the temperature and pulses the heater which then warms the water up. The warmer it is towards the correct temperature the less it pulses – the colder it is the more it pulses. There are of course other variants of aquarium heater controllers on the market.

Now that you have verified the heater is working as expected the next thing you want to look at is keeping this expensive heat inside the aquarium.

Glass in the aquarium and especially open top aquariums allow heat to dissapate and therefore the aquarium will cool down. On my aquarium what I have done is lag the sides and rear of the aquarium with polystyrene which effectively insulates the aquarium. Whilst this does not look that good they cannot be seen as the rear and sides of the aquarium are in the garage. The rear and sides of the aquarium are painted so from the front the polystyrene cannot be seen. At night I also use cover glasses over the aquarium for when the lights go off in an attempt to keep the heat in the aquarium. The sump/refugium area are also both insulated so that again heat is kept in. I do not insulate any of my overflows or return pipes as the water travels through them at such a pace that heat loss is not that great a concern.

For the aquarium which is inside the home then insulation is probably not something you would choose to do for aesthetic reasons however cover glasses could be used at night time or even all the time if fluorescent lighting is used. In this instance I would recommend that aquarium temperature controllers be investigated and purchased to control the heat more efficiently rather than the on or off methods of traditional heaters.

Of course it is also imperative that enough heating wattage is being used in the aquarium and that two heaters are used instead of just one just in case a heater failure was to occur.

As we always say – stability is key and temperature is no exception.

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Should You Use Glass Covers On An Aquarium?

Those aquarists who purchased a ready built aquarium will possibly find that glass covers are built in. They will either be ‘lift-out’ or sliding. The aquarium that’s been individually assembled by the aquarist has covers or not – another decision to be made.

If it is a fish only aquarium then there isn’t any lighting consideration to worry about. It is necessary to consider if any of the fish are known to be jumpers. If they are glass covers are usually the answer, though some aquarists use a fine mesh across the top. Where ‘jumpers’ are present, mesh is used in consideration of the oxygen requirements of the livestock as fish, particularly when heavily stocked, have a high demand. Leaving the seawater surface open to the air gives the largest gas exchange area the maximum exchange capability, provided seawater movement is adequate.

With a reef system lighting is a consideration, as most of the corals that are commonly kept on a captive reef need it at the correct intensity and spectrum. Some corals, though light loving, need less than others. Generally speaking, soft corals need less light than hard types. The glass covers need to be kept clean so that they cause minimal reduction in light intensity. Any material, including glass, will reduce light intensity to an extent. In addition, there are strengthening glass straps that run across front to back on many aquariums and another layer of glass above them will cause additional intensity reduction. I do not know what happens to spectrum if anything. Any change caused by float glass may well be minimal.

Consideration has also to be given to the type of lighting system in use. Glass covers do not usually present any problem with fluorescent tubes, but may well do so with metal halide bulbs. Metal halide lighting emits a lot of heat and this is one of the major problems for the aquarist. The emitted heat tends to warm up the seawater, and one way of cooling it down is to blow air across the surface using electric fans. This would be impossible with glass covers, which would allow heat to increase above the seawater surface. So the aquarist would be constantly checking the temperature situation in the ‘lights on’ period and removing the covers when necessary, whereas with an open top fanned air and heat escape is not a problem.

There is an advantage to using glass covers, and that concerns evaporation. Fresh water evaporates from the seawater leaving salt behind, and it is therefore important to maintain the seawater at the correct level, thus keeping the SG (specific gravity) constant. Some aquarists do top-ups manually, others with larger aquariums use automation. If glass covers are in use the rate of evaporation reduces significantly, as a large percentage of the evaporation occurs at the seawater surface. So the amount of RO (reverse osmosis) water required for topping up will be less. However, there is a disadvantage in this as well, and this is that when the lights turn on at the start of a new day there will be heavy condensation in the form of droplets on the underside of the glass. This will also have some impact on the lighting discussed earlier, until the heat from the lighting clears the droplets.

Twice, on two different aquariums, I have carried out an experiment with glass covers. Both aquariums contained a soft coral reef and were lit by an array of fluorescent tubes. For a measured period of six months I put glass covers on and watched for any changes in the corals. I was unable to detect any change at all on any coral either in growth or colour. They all remained in good health. The only noted differences were that evaporation reduced and I had to clean the covers weekly! I do not claim this to be a definitive result, but interesting nevertheless.

I do use the glass covers when I go on holiday, purely because it reduces evaporation and makes Peter’s caretaking job a little easier. When I am at home they are in storage.

It seems to me that the marine aquarist is better off not using covers. First of all, the light that is being paid for is maximized into the aquarium, and very importantly there isn’t any restriction to air reaching the seawater surface, thus as said maximizing gas exchange. Excessive heat can be more easily controlled. If there are any fish ‘jumpers’, then it is a simple matter to make a light wooden framework to fit the top area of the aquarium and stretch a small-hole mesh (not metal) across it. It would be just as easy to remove as glass covers. Finally, there aren’t any glass covers to clean or break.

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Warmer Weather

In my neck of the woods its been a glorious day, sun shining and warm. Work has been going on in the garden after I’d finished my aquarium maintenance (I start that job early so I don’t miss out on the good weather).

Later in the afternoon I walked by the aquarium and noticed that the heater controller (I have an external controller with probe controlling two heaters) indicator was not flashing at all. This didn’t cause any alarm as I assumed it was caused by the increased air temperature. A check was made though and this proved to be the case.

Now there are those aquarists who have mainly blue skies and warm – or hot – weather all the time. Then there are others like myself who have seasons, these being spring, summer, autumn and winter of course.

Those with continuous warm or hot weather could find it best to invest in a chiller (seawater cooler). Though these are not cheap, they are very worthwhile to protect the reef (or fish) from unwanted excessive temperature increases. The device should be sized to suit the aquarium, and the pump used should be in accordance with the manufacturer’s instructions, to ensure that the seawater has sufficient contact or cooling time. They are easy to set, the heaters (if any) are set to the design temperature and the chiller to 2 degrees F higher. Again, the manufacturer’s instructions should be followed.

For other aquarists such as myself the increase in temperature because of the season may be insufficient or over too short a period to justify the cost of a chiller. There are other ways to cool an aquarium.

I have a 12″ electric room fan on a small pedestal. The fan will oscillate if required but I keep it fixed. The fan is directed across the front glass of the aquarium so that the air flow runs along it. The flow of air is surprisingly cool. This air flow causes the aquarium to act like a radiator and it spills heat. Sometimes I leave it running all day, switching it off in the evening when I notice that the heater controller indicator has started to flash – that is, the seawater is cooling sufficiently to need heat.

Another way of cooling an aquarium, and it is more effective, is to blow air across the top of the seawater. This can be done with small 4″ to 6″ fans, one or more as required. The fans are fixed to the end panels of the aquarium. The potential problem with this is electricity: the fans must be stable and secure and there must be no way whatsoever for seawater to splash the fans or it could be dangerous.

A much better way is to use a room fan such as I do – 12″ or so – but buy one mounted on a taller adjustable pedestal. This means the fan can be adjusted to blow across the seawater surface but is safer as it is not near the seawater, but standing away from the aquarium.

Using fans to blow air across the seawater surface is a good cooling method, but does increase evaporation.

Any aquarist who uses a hood for the lighting system should consider the heat that could be getting into the aquarium. This applies to metal halide bulbs, and also to T5 fluorescent tubes. An array of T5’s can give off a surprising amount of heat. The output from the lighting can increase the seawater temperature on its own, but allied with warm air in the room the temperature could rise excessively.

It is not difficult to vent a lighting hood in most cases. The use of computer type fans can be of use. Need depends to an extent on the size of the hood and the number of bulbs or tubes in it. Some aquarists use two fans, one at each end. One is set to suck and one to blow, creating a continuous cooling flow of air which moves the heat out of the hood.

Another way is to put a fan (or more depending on need) in the upper surface of the hood. The fan is set to blow air out of the hood, that is upwards. Therefore air is drawn in from underneath, or vents in the ends, and the heat is blown up away from the seawater.

Of course, depending on the amount of heat being extracted from the hood, this could have an effect on the room air temperature. If the air temperature rises, it can increase the seawater temperature. In this case if air conditioning is in use then that will deal with the air temperature but will have an impact, probably not particularly significant, on the running cost. Or maybe an extractor fan can be used in the room. Or maybe just leaving a window or two open will be sufficient.

Whatever the aquarist decides, the usually simple operation will avoid the stress caused by temperature increase. A large enough increase can be a disaster.

(Note: electricity and seawater can be a lethal combination. Electricity on its own can be dangerous. If the aquarist is not totally confident in his/her knowledge and ability, then it is important to seek qualified advice.)

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Marine Aquarium Temperature

Aquarists keeping cold water systems very often employ chillers (coolers) to prevent the seawater warming up excessively. Warm water systems that are in naturally warm areas may well need to do the same to prevent overheating.

Whatever the warm water system, be it a fish only aquarium or a reef aquarium, the aquarium temperature needs to be kept stable, with only a small deviation from the design point. The majority of aquarists will employ heaters, and the rest chillers, or maybe both.

Modern heater units and chillers are reasonably accurate in maintaining temperature, usually with a deviation of between 0.5 to 1.5 deg F. Seawater is fairly slow to cool and warm, so these changes are acceptable. Wider changes in temperature can cause stress to livestock, the worst affected probably being corals.

On the wild reef seawater temperature is for the most part stable throughout the year. Average temperatures on these reefs are 82 deg F *. Note that this is an average, meaning that some are cooler and some warmer. It gives an idea of where the temperature in an aquarium could be set. Setting the temperature in the aquarium to 82 deg F will give a general average temperature approximation. So is that the temperature to use? As said the temperature is an average – there are variances between reefs and there will be differences at various depths.

The lowest temperature that should be used is more easy to state. Coral reefs (of the warm water kind) do not develop if the seawater temperature is 65 deg F or less. So the temperature must be higher than 65 deg F. However, this is too low for organisms to have a high enough metabolism and it is most likely they came from much warmer water, so they would decline rapidly and die. The lower water temperature acceptable is 75 deg F.

Some aquarists set a temperature at between 80 and 84 deg F. This is done because the metabolism of the whole aquarium is raised – fish, corals, shrimps and the tiny life forms in and on deep sand beds (DSB) etc. This increase in metabolism should mean faster growth. Fish will demand more food, this food will be digested and waste will be processed more quickly. So all should remain more or less in balance. Well, yes, it should. However, the aquarist is moving closer to the edge. The aquarium has a small gallonage no matter how large it is when compared to the sea. The water can heat more quickly. If the temperature is already maintained above 80 deg F, then it is a quicker journey to higher temperatures and potential trouble. What if a heater malfunctions in the ‘on’ position? What if metal halides are in use (the heaters will turn off but the water could continue to heat)? Additionally, seawater that is cold has more oxygen than warm seawater. As the temperature continues to rise oxygen continues to reduce. This could cause trouble in any system, but particularly in a heavily stocked fish only one.

In a well managed aquarium the oxygen question should not arise. A protein skimmer is no doubt in use. Also, adequate water circulation will provide efficient gas exchange maintaining oxygen levels. The point is, the potential for a problem is there.

Apart from potential problems with the example oxygen, maintaining higher temperatures is going to cost more in electricity, except for the aquarist who has to keep temperatures down with a chiller. This is, or should be, a secondary consideration of course, it is the welfare of the livestock that is being considered (and the aquarist: if livestock are healthy and vibrant then the aquarist will be happy).

So, what is the best temperature setting? Lower down, the livestock will have a slower metabolism and oxygen will be more plentiful. Higher, the opposite. It seems a compromise is in order. I would suggest a temperature setting of between 77 and 80 deg F. This is somewhere in the middle of the acceptable range and gives a reasonable safety margin should a heater malfunction etc.

I run a soft coral reef at a temperature of 77 deg F. The corals grow at a reasonable rate – they need cutting fairly regularly. The fish display good appetites, and the DSB has a high population of miniature life forms. I should mention that I have never experimented with higher temperatures – but then, why would I when all is well.

Whatever the temperature, it needs to be stable. Constantly changing the temperature setting will do no good at all. If the aquarist wishes to experiment with higher settings, then the temperature should be increased slowly over a considerable period. The same applies to temperature reduction of any amount. The aquarist who sets a high temperature needs to ensure the heater/stats in use are of high quality, and preferably there is an external heater control with an in-tank probe in use.

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

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