Disease!
July 24, 2009
The very word can strike fear into any marine aquarist. Diseases, particularly ‘velvet’ and ‘white spot’ are real threats.
The threat can be minimized of course. Careful selection of fish is the initial way, being careful to ensure the selected ones are as ‘clean’ as they should be. Other intended livestock should also be carefully inspected.
A second line of defence is the quarantine tank where any disease can be treated and cured before it is introduced to the main display aquarium where it creates a threat to other livestock. Strangely, most marine aquarists do not make use of quarantine instead introducing their livestock direct. This is taking a chance as dealing with disease especially in a reef system could be difficult – difficult because copper, the number one treatment for certain diseases, is deadly to corals.
The question of disease and its treatment is wide and quite varied. Most marine books have a section on disease which can be of assistance.
Here are two videos which deal with the subject, they are good quality and actions are clearly explained. A large part of the videos deals with cleaning up the aquarium prior to medication. Obviously the instructions on the medication container must be properly followed relative to the net gallonage of the aquarium. Finally, as already mentioned copper should not be used in a reef system – if there is any doubt check the medication manufacturer’s instructions and suggestions.
An Attached Quarantine Tank
July 18, 2009
Having a quarantine tank is generally accepted as ‘a good thing’. Strangely, the majority of marine aquarists don’t use one, instead throwing caution to the winds or at least relying on good luck. Perhaps they obtain their fish from sources where they are guaranteed to have been successfully quarantined.
Anyway, this isn’t about the merits of quarantine, this is about continuing usefulness.
Quarantine tanks don’t need to be large, just large enough to comfortably hold the largest fish that will occupy them. All the same, it is a little irritating to have an available space doing nothing – the tank sits there empty. The tank can of course be used as a hospital tank should the need arise, but this is hardly ever needed particularly if quarantine has been completed on carefully selected and compatible livestock.
An idea came up recently about a way of using a quarantine tank as part of an overall system so that it wouldn’t sit and ‘do nothing’.
The tank would be selected to ensure it could accommodate anything likely to go in it. It would then be connected into the main system permanently. Err, sorry, what was that again?
Instead of the quarantine tank sitting empty most of the time it would be connected to the main display system as a permanent feature. This gives the advantage that the system would hold more gallons of seawater. It would not be intended to be stocked with anything, just have seawater flowing through it. (Hmm, how long would that last I wonder, aquarists tend to fill empty spaces.)
The tank would be fed seawater that was circulating through the display aquarium and any sump. See the first problem? Of course you can, any problem in the tank would become an available problem throughout the system. Disease for example, the very thing that the quarantine tank is designed to prevent entering the main display.
The idea went on that this problem could be prevented by using a UV (ultraviolet) sterilizer. UV sterilizers (some call them filters) kill or severely damage unwanted organisms as they pass close to the UV light (they do the same to good organisms as well). The seawater exiting the quarantine tank would flow through the sterilizer and therefore anything unwanted would be dealt with. On the face of it this isn’t a bad idea.
The first problem is that the flow rate through the UV unit has to be correct. This is because in order for the UV unit to be effective organisms have to be exposed to the radiation for a long enough period. Therefore the flow rate would probably have to be slowed down.
The second problem is that good as a UV sterilizer is there isn’t a guarantee that all organisms passing though will be killed or sufficiently damaged. Most probably would be or the UV sterilizer wouldn’t exist – but there isn’t as said a surety that all will be properly dealt with. So the system as a whole would be at risk.
The next is not really a problem, more a discipline. The aquarist would need to ensure that the UV bulb, which has a specific life, was renewed well in time or its effectiveness would reduce.
So the basic idea is flawed. However, how about a small modification? How about placing a shut off valve on the outlet from the tank? This would require a complication which is another outlet for the seawater to go through the UV unit. This would be easily achieved by fitting in a correctly rated powerhead to run seawater through the UV unit and back again. Oh, there’d need to be a shut off valve on the inlet to the tank too or it would overflow. Things are getting a bit too complicated. With the shut-off valves at each end of the tank it is now independent of the system.
Many aquarists use a UV unit fulltime or part time or as necessary. Fine, there’s no problem there. Many aquarists don’t use them at all. It’s a choice. But the UV sterilizer is not an answer to the quarantine question.
The only way a permanently attached quarantine tank could work, as far as I can see, is to have stop valves on the seawater input and output. Therefore the tank could not be plumbed directly in line with the display aquarium and sump, it would have to have a direct feed to and from the seawater source which wouldn’t interfere with overall system circulation.
Under normal circumstances (that is, empty without livestock) the quarantine tank would be full of seawater flowing through it, which is an advantage to overall gallonage. If the time came to use it as a dedicated quarantine area, the first action would be to turn off the input and output valves to isolate the tank.
Another problem now arises and that is seawater circulation. Now that the tank is isolated there isn’t any circulation so there would need to be available a low powered powerhead to deal with this. The next problem is that the circulating seawater would cool down, so a small heater would be needed. Then, for the security of the quarantined fish, a suitable clay pot, for example, would be needed as a temporary home.
Light needs to be considered – is there enough light over the quarantine area? Would any need to be added for the comfort of the fish?
Once the quarantine period was over, before the inlet and output valves were opened, all the seawater in the quarantine area would need to be removed. Most could probably be siphoned out. It would be important to dry out the tank entirely particularly if any copper treatment had been used, and probably rinse the area out as well. Not particularly difficult, but another necessity and complication.
All of this leads to the thought that it would be better to stay with the unattached quarantine tank. They are usually small and can be put out of the way somewhere with the powerhead and heater inside.
Having an additional tank attached to the main system isn’t a bad idea, as said it increases gallonage. Also it could house further filtration or even special livestock of interest to the aquarist. There wouldn’t need to be inlet and outlet stop valves either!
There is one thing that must be said and this is that thinking ‘outside the box’ is one of the ways that the hobby progresses, so the aquarist who mused over this idea is to be congratulated – the idea is not practical when examined, but it is an idea.
Things Change
July 16, 2009
Pretty obvious really! The weather is an example. But no, we’re concerned with marine aquariums of course.
In a fish only aquarium the changes are usually, strangely enough, to do with fish. New additions, growth, the cave/hole they live in and the like. In a reef system more changes are often noticeable.
On the wild reef changes occur slowly for the most part, though things could happen quickly. If a storm comes along then coral formation could change as corals are broken. Unfortunately change can also happen quickly (in terms of the life of the reef) caused by man-made pollution and interference. Normal reef changes are when one coral slowly dominates another in a long drawn out battle for space, or coral colonies spread over new areas.
So change is quite natural. In the aquarium changes could be unnatural, that is caused by the aquarist. An example is the cutting of corals because of growth. When corals grow they could shadow or at least reduce the light available for others and in addition the seawater flow could be altered, meaning that some corals do not receive the flow they require. So the aquarist cuts the corals to maintain the balance of light and/or flow. This is a quite drastic change that doesn’t occur in the wild of course. Overshadowing will occur to some extent though. Hopefully the aquarist having cut corals will ‘frag’ them so that additional good comes from the exercise.
Other changes can occur and this unfortunately includes coral failure. Nowadays with the greater amount of knowledge available failure in this area should be much reduced. However, failure can occur in more than the usual way, the usual way being that a coral is just not happy, closes and shrinks away quite rapidly.
In my soft coral reef there is a colony of green star polyps, which are sometimes called star polyps or daisy polyps. The proper name is Pachyclavularia purpurea (some call it Clavularia viridis but this is incorrect)*. Anyway, the thing is that this colony arrived six years ago on a rock which was completely covered. The rock would be generally about 6 inches across at the base and about 4 inches high. After a while the coral spread onto a neighbouring rock and completely covered that as well. There wasn’t anywhere else for it to go so it stopped spreading.
For a long while it just came out at ‘dawn’ and went in at ‘dusk’. It was perfectly healthy and also completely at home, happy with the lighting and seawater currents. It was attractive and added to the many colours of the display.
Eventually I noted that it was beginning to climb onto itself that is it had nowhere to go except to cover itself. So the mat was spreading and new polyps were opening on top of the original.
I was quite concerned about this as I thought first of all that the lower layer could lose adhesion – but it didn’t. The spread across a lower layer continued for a long while, years in fact and eventually the colony was higher than it had been originally because of the layering. I was pleased in a way as the shape of the colony had altered; it no longer followed the shape of the rock but had formed mounds and spires plus some flatter surfaces, making it more interesting.
This situation continued until I noticed that some of the colony, a small area only, didn’t have any extended polyps. Sometimes the colony had not expanded for a whole day or so on previous occasions, therefore I wasn’t concerned.
However, the polyp areas that failed to expand extended in area. Eventually I noticed a bare area of rock down near the base. This area extended until very nearly all of the rock was bare. Some of the remaining un-layered matt containing polyps was removed and placed elsewhere in the aquarium and this is opening normally, appearing to be beginning to form a new colony.
Apart from one area on the adjacent rock that was colonized there wasn’t anything left. The reduction and loss happened over about a period of two months, which isn’t very long.
It isn’t all bad news though. I’ve recently noticed that a few odd polyps have appeared on the rock and hopefully these will lead to a re-colonization. If this occurs then I’ll recover the original colony and have an additional transplanted one.
So why did this occur? All other corals are fine, expanded with proper polyp extension. It follows that seawater quality and lighting are also as they should be.
I reckon my original fear that the original matt could lose adhesion was not the reason for the die-back. Adhesion loss could of course have occurred but the colony remained in place.
It seems to me that as the colony for the most part actually disappeared then it must have ‘dissolved’, or rotted away. This could have started with the covered lower layers rotting, which would have caused the top layer to become affected.
What I have to do now is wait and continue observing the polyps that remain, both the two small colonies and the separate polyps. Hopefully the original colony will grow back to full size.
If full size is achieved then perhaps the colony will eventually begin to overgrow itself. This would presumably mean the colony will eventually fail again. The possible way out of this is to put a bare rock alongside the re-generated colony which can be grown over. This can be placed elsewhere in the reef or given away.
As in the wild changes occur with the captive reef. It all makes the hobby so interesting, don’t you think?
The photos (taken by me so not of professional standard!) show the area where the original colony existed alongside the rock that was colonized, where some of the coral remains. The other photo, taken closer in, shows the polyps that have appeared that give me hope that a new colony will re-generate.
(*Reference: Aquarium Corals. Eric H. Borneham)
Conversions
July 11, 2009
Here are a few conversions which could be useful to someone, you never know. The ones shown are those that could be applicable to aquarists, maybe!
To find volume.
Multiply length by breadth by height. (If finding the water space volume of an aquarium it is more accurate to measure from the water level. It must also be remembered that volume will be taken up by rocks and sand.)
Cubic inches to cubic centimeters – multiply by 16.3871
Cubic feet to cubic meters – multiply by 0.0283
Cubic centimeters to cubic inches – multiply by 0.061
Cubic meters to cubic feet multiply by 35.315
Converting Centigrade to Fahrenheit.
C F
24 75.2
25 77 (the temperature many aquarists use)
26 78.8
27 80.6
Length.
(10 millimeters = 1 centimeter)
(1 inch = 2.5 centimeters)
Inches to millimeters – multiply by 25.4
Feet to meters – multiply by 0.3048
Millimeters to inches – multiply by 0.0394
Meters to feet – multiply by 3.2808
Area.
To find area multiply length by width.
Square inches to square centimeters – multiply by 6.4516
Square feet to square meters – multiply by 0.0929
Square centimeters to square inches – multiply by 0.155
Square meters to square feet – multiply by 10.764
Capacity.
UK fluid ounces to liters – multiply by 0.0284
US fluid ounces to liters – multiply by 0.0296
UK pints to liters – multiply by 0.5682
US pints to liters – multiply by 0.4732
UK gallons to liters – multiply by 4.546
US gallons to liters – multiply by 3.7854
Liters to UK fluid ounces – multiply by 35.1961
Liters to US fluid ounces – multiply by 33.8150
Liters to UK pints – multiply by 1.7598
Liters to US pints – multiply by 2.1134
Liters to UK gallons – multiply by 0.2199
Liters to US gallons – multiply by 0.2642
Weight.
Ounces to grams – multiply by 28.3495
Pounds to kilograms – multiply by 0.4536
Grams to ounces – multiply by 0.0353
Kilograms to pounds – multiply by 2.2046
(Reference: The Chambers Dictionary)
It Takes Time
July 6, 2009
Any experienced aquarist can understand why a newcomer to the hobby really wants to see some livestock in their aquarium, because those aquarists have been through the same process.
Doing things properly is a patience tester. This isn’t a bad thing because patience is at or very near top of the list of attributes that are very advantageous to a marine aquarist. It starts from the word go. First there is the question of the aquarium size and position and also perhaps a bit of diplomacy with the other half. Then there is the question of equipment and its cost, perhaps when the equipment list was complete and also running costs checked, mainly electricity, the aquarium needed to be downsized a little (in itself highly commendable if cost is a question, better to find out early). Collecting the equipment could have taken a considerable period, relieved from time to time by the excitement of opening another box.
Then the aquarium and equipment are all together. Great, off then! Oh no, there it goes again, slow down, use patience. This is at the stage of livestock of course. The aquarist is well aware of what system it will be, usually fish only or mixed reef (there are some coral only systems about). Having done the research the reason for slowness in stocking becomes clear: the bio-filter. This is the life support for all the life within the aquarium. Without this support it wouldn’t be long before trouble struck, probably with tragic consequences.
The aquarist could be using live rock which is supplied ready for use, or cured (it can be supplied uncured leaving preparation to the aquarist, but the normal is cured). This live rock contains the bacteria necessary for dealing with toxins, namely ammonia and nitrite. These two toxins are deadly and the only acceptable level is ‘undetectable’ or zero. (Live rock should also be able to deal with nitrate within reason, but nitrate is not a toxin in the sense that ammonia and nitrite is.)
Or perhaps the aquarist has chosen a canister filter(s) to provide the bio service. This is fine, though it needs to be remembered that nitrate will be produced by this system and not removed. There aren’t any bacteria present in the canister filter at the beginning, they need to be kick-started. This can be achieved in several ways, though the best is using commercial maturation fluid and following directions.
So the stage is set. Whether it is a ‘matured’ canister filter or live rock, the aquarium should not be fully stocked.
In the case of the canister filter the maturation is primary. There is a bacterial presence to deal with ammonia and nitrite but the bacteria are new and probably few in number. It takes time for them to build and adjust to the full aquarium load. Placing a full aquarium load (or bio-load) would overpower the abilities of the bacteria to cope and disaster would follow. The bacteria would increase because of the high presence of toxins but not fast enough.
What of live rock? This is purchased hopefully with bacteria present. It is fairly certain that bacteria will be present but are there enough to deal with the full bio-load? It must be said that there could be, if the live rock has just been cured and is new for sale. Even then it isn’t certain though. Also, what if the live rock had been in the ‘for sale’ tank for a considerable period, as much of it is? All life needs food and this includes bacteria. If the rock has simply been sitting in a tank then the bacterial count could drop and be quite low.
So we’re back to the beginning, with the words patience and slow. With both live rock and canister filtration, stocking particularly with fish should be slow. This enables the bacteria that are present to have a chance of dealing with toxins which of course is good for the fish and the aquarist. Failure at such an early stage is not pleasant. As time progresses and the bio-load increases the bacteria populations also increase to keep pace and have a good chance of achieving this if stocking is slow. Eventually full stocking is reached and the bacteria then settle down to handling a more or less level load. Once this stage is reached and about three months have elapsed then the bio-filtration can be considered to be stable.
During the stocking period regular testing is required to ensure the bio-filtration is coping. This is easily achieved as ammonia and nitrite tests will hopefully show zero for both. If any reading does appear further stocking should cease and close control on feeding is needed. The readings should disappear and after a week or so of zero readings cautious further stocking can proceed.
During the stocking period routine seawater changes should be completed, these changes continue for the life of the aquarium. The guideline amount to change is 10% of the net seawater gallonage per week. This amount could be flexed once the aquarist has some experience and knows the traits of the aquarium, such as nitrate increase if any.
So what does the word ‘slow’ generally mean in relation to stocking? There are varying opinions though quite often the advice is to ‘stock slowly’ and nothing else, which isn’t particularly helpful.
Corals present a quite low bio-load in the aquarium and it is considered general good practice initially to sparsely populate the reef with the desired corals, which means they are spaced well apart. Later when it is apparent there is space available more could be added. It also gives time for the aquarist to see the extent of expansion that many corals exhibit. Those that do expand, and also those that don’t, grow. Corals of differing types should not touch. A reef that looks overcrowded probably is.
Fish present the biggest load for the bio-filtration to process. When a fish is introduced, feeding also needs to start, so the work of the bio-filtration really begins. The aquarist should have done research on the fish and know their habits and potential final size. It is good practice to put more timid or peaceable fish in earlier than robust and/or more aggressive types.
It cannot really be stated that an additional fish could be placed in the aquarium after every X period. The size of the fish needs to be considered. If a small fish is placed in the aquarium, then of course the bio-load will increase. After a period (see below), if all is well with seawater tests, then a further fish could be added. This also has the advantage that if the initial fish is timid then it has time to settle and become confident in its new home. The next fish could well be a small one too, so the same applies. A further fish could well be larger so it is good practice to increase the time allowed before any further addition, as the larger the fish the bigger the load it places on the bio-filtration. If the fish is an inch larger, allow an extra week. Proceed in this way keeping a close eye on seawater conditions and feeding carefully (meaning minimize excess) and all should be well.
There is a guideline for time periods between fish additions. This is general and not intended to be rigid in any way, particularly if an aquarist is not sure if all is well. In that case, wait! The general guideline is ‘a week an inch’. So if that is followed a two inch fish would require two weeks before another fish is introduced. If the next fish has a length of three inches then a three week period is required, and so on. The fish length excludes the tail. I’m not aware of any scientific evidence supporting this guideline, but it is sensible and works.
If the marine system has been well thought out, once the seawater has been placed into it and livestock is introduced it is the birth of a new mini aquatic world. Everything should be in balance as far as possible. The lighting should suit the corals, the corals should be properly spaced with sufficient seawater movement and the fish should be mutually compatible and suited to the system design, be that fish only or reef. Supporting the aquarium life is the bio-filtration which is absolutely essential.
The foundation for future success is current practice. Give Mother Nature’s bacteria time and they’ll do the job.
Why Should Alkalinity Be Higher In The Aquarium?
June 28, 2009
The marine aquarium can be so beautiful if the aquarist does straightforward routine maintenance as required, and doing this maintenance includes attention to the all important seawater quality.
Seawater quality is maintained by routine changes of sufficient quantity, and at the same time tests are completed to ensure that the required standards are met. These tests include specific gravity (SG), pH, nitrate and for a reef could include calcium and similar. Some aquarists continue to test for ammonia and nitrite after the initial maturing process. Alkalinity is a test that is useful to marine systems too.
It would seem fair to think that Mother Nature would know best in these matters and the alkalinity level in the wild is 7 to 9 KH*. So perhaps we should keep out aquarium seawater at the same level.
We could maintain a natural level and hopefully all things being equal there wouldn’t be any problems. However, we are not talking of the vastness of the seas and oceans where seawater quantity is measured in cubic miles; we are talking about aquariums where even a large home system of 500 gallons is, by comparison, very tiny.
Most aquariums are fully stocked whatever system they are. The life in the aquarium puts pressure on the seawater in several ways and one of them is the acid/alkalinity balance. We know this measure as it uses the pH scale, and we want a pH of between 8.0 and 8.4 which is on the alkaline side. The life functions in the aquarium constantly try to reduce this pH towards the acid side, something we do not want.
Prevention of the reduction in pH is achieved by the ‘buffering’ capacity of the seawater, in other words its ability to resist changes caused by acidic substances. The ‘buffer’ is mainly the carbonate/bicarbonate content of the seawater. In certain circumstances the buffer could be seriously weakened or even exhaust and the pH would fall which is detrimental to the livestock.
Dry seawater salt as purchased by most aquarists for seawater make-up has a buffering capacity usually around natural levels. However, many aquarists boost the buffering capacity of their seawater by adding carbonate/bicarbonate powders. These powders are usually mixed in some seawater before being added to the aquarium, being careful not to hit corals etc. The powders are sold commercially and are very easy to use.
In an aquarium it is considered best to maintain alkalinity from 8 to 14 KH.* It is not recommended to raise the level above 14 KH.* The recommended level of 8 to 14 KH does not mean the level can vary within these limits, it should be reasonably stable at the chosen point, ‘reasonably’ meaning that some variation over say a week will not usually be harmful. My system runs at 10 KH and needs boosting to an extent weekly.
If the aquarist measures the alkalinity of a fully stocked system on a weekly basis and keeps a note, then the trend of the aquarium can be seen. The amount of buffer that needs to be added is easily prepared week to week. Testing can be reduced once this requirement has been discovered but should not be abandoned.
If pH is a problem and it is falling despite routine seawater changes and good husbandry in feeding etc, then perhaps the buffer capacity needs attention. Increasing the buffer by 1 KH week to week will not do harm. I have found a good alkalinity level is also beneficial to the growth of welcome encrusting algae which can beautify the aquarium.
By the way, if the desire is to measure alkalinity by mg/l, then multiply KH by 17.9.
(*Reference: Marine Atlas. Helmut Debelius & Hans A. Baensch)
A Worrying Failure
June 23, 2009
Marine aquarists make use of varying types of equipment on their fish only or reef aquariums. This equipment is generally reliable nowadays but nevertheless any device has the potential to fail.
There are many canister filters in use for either mechanical or bio-filtration. Though live rock is the bio-filtration of choice for the modern aquarium, canisters are still in use by many for this essential task. There isn’t any reason why they shouldn’t be, though there are drawbacks.
Live rock is able, within reason, to deal with nitrate. In other words live rock should perform the full nitrogen cycle. This is the major drawback with canister filters, nitrate is the end product. This is because the bio-media within the canister is oxygen rich and there isn’t any need for oxygen to be obtained elsewhere. Nitrate reducing bacteria require an environment very low in oxygen which forces them to seek an oxygen supply elsewhere; nitrate is present so oxygen is taken from that which breaks the nitrate down. It follows that an aquarist using a canister filter needs to keep a closer eye on nitrate levels and carry out the requisite correctly sized seawater changes.
Another advantage of live rock is that there isn’t anything to break down, as opposed to a canister filter where there is an electric pump. As already said modern canisters are reliable though recommended models should be sought when purchasing, but what if a breakdown does occur?
Failure of the electric motor means that the whole function of the canister ceases as seawater flow stops completely. When an aquarist does routine maintenance the output from various devices is checked, an operation that takes hardly any time. However, it is more likely than not that a failure will occur at an inconvenient moment. Canister electrics are usually very quiet nowadays and there isn’t any indication of trouble apart from seawater output ceasing. So the first thing is to note the output anytime possible, such as at feeding time and when starting to simply observe and admire the aquarium. It only takes seconds.
A stopped canister filter should be switched off and then on again a couple of times, this sometimes frees up the motor. Don’t count on it though! If the motor does re-start then as soon as possible check the shaft and impellor for debris. However, before attempting to re-start by switching off and on note the comments in the following paragraphs.
Once the output from the canister is noted to have stopped there isn’t any way of knowing when it stopped. This is a worry because involved is the life support for the system, the bacteria. How are they faring?
It could be that the fish have been acting strangely and that is how the lack of seawater output was noticed. If this is the case then the failure occurred quite some time ago as there has been time for toxics to build up in the seawater. The first action is a seawater change, the size of which depends on the severity of the situation. If the fish are really obviously in trouble then 25% is not excessive, more if necessary, and the change should be done as soon as possible. The aquarist should be prepared to carry out a further change if necessary.
The aquarist should ensure that other equipment, namely the protein skimmer and seawater circulators, are working at maximum efficiency to ensure maximum oxygen intake and minimum bio loading (the skimmer should remove substances reducing the load on the bio-filter).
A regime of seawater testing should be introduced. Once the situation is under control the tests can be done once daily, but it is often better and more reassuring for the aquarist to do tests morning and evening. The tests are of course ammonia and nitrite. The only ongoing acceptable test result is ‘nil’ or perhaps more accurately ‘undetectable’.
If it is found that the canister filter electric motor has failed but the fish are not showing symptoms of distress then the failure is probably quite recent. Again, test the seawater and do a change if necessary.
In both cases, fish distressed or not, cease feeding until an effective bio-filter is back in operation.
The speed that toxics develop in the seawater depends to a large extent on the fish numbers present. Corals present a far lower bio-load.
As soon as possible deal with the canister filter. At this point it is known that switching it on and off didn’t work! Ensure it is switched off and disconnect from the tubing. Check the impellor and shaft, there could have been a failure, if jammed the problem can usually be sorted out. If there is a breakage spares are usually available, obtain them by the fastest possible means even if it incurs extra cost. (Obtain the spares from the local fish shop if possible to avoid any delay.) Check that the input and output tubing is not blocked, this could occur over time.
If the electric motor itself has failed then a new canister filter should be obtained (or better two, see below). When the replacement device is available bio-media can be transferred and if required extra added. Until the new device arrives the bio-media already held should be kept within the aquarium seawater preferably in a high flow area so that at least some of the bacteria are retained. When the new canister is running there is a clear need for monitoring the seawater condition, as it will be similar to though not as extensive as maturing again. Seawater quality can be maintained by additional seawater changes, new seawater should be available at all times until the aquarist is sure all is well.
If the canister has been off for a long time do not re-start it and allow it to continue running. Disconnect and drain the internal seawater out completely. Refill and then start and run. This is because there is a danger that the seawater within the canister could be heavily contaminated. If the canister is likely to have been off for only a short period, just re-start. It is worthwhile carrying out daily seawater tests for a week in either case to ensure the bio-filter is effective. After re-start, feeding should be with considerable caution as the bio-filtration may well be weakened and need to re-build. Again, ensure that the protein skimmer and seawater circulation pumps are at maximum efficiency.
To largely avoid a problem such as described, unlikely as it usually is, when the system is designed it is a good idea to employ two canister filters. This will of course mean a little more cost, but the filters can be smaller. Instead of obtaining one which can handle the net gallonage of the system, obtain two. These together in total should handle the net gallonage, but it is a good idea to have both of them a little oversized. They can be routinely serviced alternatively so there isn’t any extra work generated. If the need for canister bio-filtration is removed in the future they are useful for mechanical or other types of filtration.
It is generally unlikely that a modern canister filter will fail, particularly if it is adequately routinely serviced. If it does fail the shaft/impellor could be affected by accumulated debris and/or calcareous buildup, or tube blockages could be present. Observation is the main preventative.
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