Relating to marine aquariums what is meant by ‘mature’? It means that the aquarium system is ready to support life. In fact there are two levels of maturity: the first is the initial level which is achieved after the system has been set up and the biological filter (some call it life support) has been activated. The second is when the system is truly mature, this is when the livestock is present in entirety and the biological filter has fully settled down to the task it faces, this could take many months. The first level could take many days to weeks.
The two main biological filter systems in use are live rock and canisters, the first being the most desirable. The biological filter is populated by bacteria. The bacteria deal with the toxics which, without them, would appear in seawater tests, these being ammonia and nitrite. Ammonia is produced by fish etc as a natural part of life and the bacteria convert ammonia to nitrite and then nitrite to nitrate (depending on the type of filter). In an enclosed system ammonia and nitrite are dangerous and should measure on tests as zero.
It is necessary initially to look at both types of filter separately so let’s start with the canister filter.
The canister filter is an electric pump positioned on a cylinder so that seawater can be moved from the display aquarium through the canister and back to the aquarium. It’s generally best to have the seawater intake at one end of the aquarium and the outlet at the other end, with the returning seawater exiting at the surface (this is to aid with re-oxygenation). As the seawater goes through the canister the bacteria that live on the media carry out the conversion of toxics. When the canister is first set up there aren’t any bacteria present of course. It’s necessary for the aquarist to carefully choose an adequately sized canister then obtain bacteria friendly media (some are better than others) in sufficient quantity. The bacteria have to be introduced to the media and this is best done by the use of commercially available maturation fluid which includes full instructions for use. The procedures are simple and involve regular testing for ammonia and nitrite. The filter is considered mature when readings are zero, indicating that the bacteria are doing their job.
Note that canister filters do not deal with nitrate (because of the presence of oxygen). Some types of media have claimed to be able to deal with nitrate but this ability is usually short lived. To avoid putting undesirable nitrate into the aquarium from the start before livestock are present, put intake/exit tubes into a bucket containing seawater at the required temperature. When tests indicate zero for ammonia and nitrite the filter is ready to support livestock in the display aquarium. The seawater in the bucket should be thrown away. It isn’t necessary to have the filter attached to the aquarium initially: the bacteria are being introduced to the filter media not the aquarium. In the future as the aquarium slowly matures to the second level bacteria could appear elsewhere but it’s the canister media that’s the main home for the hard working bacteria.
Live rock is probably the most used filtration. Not only does it provide the bacteria media, it ‘seascapes’ the aquarium as well. There aren’t any trailing wires or tubes to be seen. All that is required is for the aquarist to purchase sufficient ‘clean’ rock and introduce it to the aquarium making sure that there is good circulation around and, as far as possible, between the rocks. ‘Clean’ (or ‘matured’) rock is that which has been kept for a period by the retailer so that organisms that are dying or dead can be cleared away. These organisms are there because live rock comes from the sea and some of them cannot withstand the stress of transportation. If dying or dead organisms were left they could be a source of ammonia. In addition, there could be undesirable organisms that hopefully will be spotted and removed. If the aquarist is lucky some desirable organisms could survive.
Live rock is able to deal with ammonia, nitrite and in addition, within reason, nitrate (‘within reason’ means there’s a limit). This is because the bacteria require oxygen, those on the surface get it easily and convert ammonia and nitrite but those within the porous rock don’t but still require oxygen – to get it they remove oxygen from nitrate thus breaking the nitrate down.
Ok, so the aquariums set up and there’s a troublesome reading of ammonia or nitrite that shouldn’t be there.
First of all, with the canister, is the aquarist using that all important requirement patience? The time required for a canister to initially mature varies and the need is to wait until it does. Don’t overdose the maturation fluid thinking that the process will speed up, it won’t. Follow the instructions carefully and stop dosing when indicated, often when the test turns red. What is happening is that the bacteria are building their numbers so that they are able to deal with the toxics present. If the filter media is ok and the pump operating correctly, the bad reading will go, often disappearing in a very short period, sometimes in not many hours. The sequence of readings is usually ammonia, then nitrite, then these clear. Nitrate often appears as the cycle progresses.
If the tests showed zero readings but a bad reading has returned, presumably this is during stocking. Stocking the aquarium starts when the initial maturation point has been reached. Stocking, particularly with fish, much less so with corals (corals present a lower biological load) should be done slowly. After the introduction of two small fish or even just one (in a 50 gallon aquarium) there should be at least a two week period before further fish are introduced, and then just two more, or one if it is larger. The reason is the biological filter has to adapt to the increasing load – if organisms are introduced too quickly the bacteria can’t cope and an undesirable test result is likely. Stop stocking and wait for any bad reading to go keeping an eye on fish already present. If they show signs of discomfort, carry out a partial seawater change. Testing should continue very regularly during the whole stocking period.
If a bad reading appears after full stocking is reached or is being approached and even after waiting it doesn’t disappear, check the canister filter. Is the electric pump working (is seawater coming out of the exit pipe?) They are generally reliable nowadays. Are the inlet and exit tubes properly attached? Is there a blockage preventing correct seawater flow? If no problem is found and the bad reading persists, check the capacity of the canister – manufacturers usually indicate the gallons the canister can deal with. If the canister can’t cope, mature a bigger one (mature the additional media and when ready transfer the media from the smaller canister). Perhaps there is room for more media in the smaller canister. Obtaining the correct size canister is clearly best done at the planning stage.
During maintenance, the bio-media within a canister filter can be cleaned if necessary to maintain seawater flow and general efficiency. The cleaning should be done in warm seawater (the old seawater after a routine change for example). Stir very gently. Never clean in tap water or there will be bad readings on testing!
The aquarist who uses live rock should adhere to the stocking principle outlined above. Some beginning aquarists believe that when live rock is introduced then stocking can go ahead as the rock is fully ready. This is incorrect and could be the reason why a bad reading has appeared.
Live rock is already populated by bacteria, but the adequacy of this population varies. First there are different types of live rock and the amount needed of a particular type should always be checked. Second the rock has to be cleaned as indicated above and in this period the rock lays quietly in seawater without livestock. Therefore there isn’t any ammonia being generated to support the bacteria’s needs and the population could reduce. To counter this, dead organisms could be producing ammonia and it is possible, for a time anyway, that the bacterial count could increase. The clean rock then goes into sale tanks where often it lays without livestock. Again the bacteria population could be decreasing. If the rock lays in a sale tank for a long period the bacteria count could be seriously depleted. It is always worthwhile checking how long since the rock was cleaned. Even with this knowledge the adequacy of the filtration ability of the rock will be unknown, hence the slow stocking.
If a bad reading appears during stocking then stocking any further should be postponed until the reading is correct – in other words until the bacteria can handle the bio-load. If the stocking is nearly complete or fully so and a bad reading appears and does not correct, then it is possible that there is a seawater circulation problem. If a check of the circulation pumps shows no problem then it is probable that the amount of rock is insufficient for the bio-load. Rock as desired should be purchased and introduced and a close watch on seawater test readings maintained. Always ensure that there is adequate seawater circulation when the new rock is introduced and of course that it is stable.
The maximum stocking level relevant to the net gallonage of the display aquarium should never be exceeded.
Generally, with canister and live rock filtration, it’s more likely to meet a problem with a fish only system than a reef one, all things being equal. Why is this? Fish present a higher bio-load to the bacteria than say corals. In a fish only system there are usually many fish for the size of aquarium, and they are all of course fed regularly. In a reef system, as said, the corals present a much lower bio-load and if there are fish present they are often smaller and should be less in number.
It’s not likely that serious problems will appear in a new aquarium system provided the aquarist prepares the system for the bio-load it will contain, that is fish only, a mixed reef system, or corals only. The new aquarist should always display patience, harder to do than might be thought. In a complete system a sudden problem is unlikely if maintenance is properly applied as anything untoward will become apparent in good time, particularly as the aquarist will have gained experience and understand the system thoroughly.