The marine aquarium hobby was once viewed as very hard, very expensive, and needing a touch of magic. The first two were correct, but not the latter, that simply being how it probably appeared to anyone not in the hobby but perhaps with a spattering of knowledge. There was little knowledge of the needs of captive marine life, and for the most part (the biggest most part) only very hardy life in very small numbers survived for any length of time, and that was usually measured in months.

I can just see those pioneer marine aquarists sitting arguing over the possibly best way to proceed. If they could see us now, their flabber would certainly be gasted.

The first real breakthrough in filtration came with the under-gravel filter. I hang my head in shame as I forget the aquarist who did it, but a plate was put under the sand and water pumped through it to keep the sand clean. Keep it clean physically that is. However, after a while it was noticed that life was surviving for quite a while, much longer than usual. So experimentation ensued, with the same results. Eventually the reason was obtained for the extended life of the livestock (from a scientist maybe?) and of course the reason was that an army of ammonia and nitrite destroying bacteria had been established. Despite my lean knowledge of the event (I’m not that old!), I do recall that the aquarist didn’t believe that the answer to keeping marine life could be that simple, he continued to believe that it was because the sand was clean.

Anyway, the door was open. Filtration capable of supporting marine life had arrived, or at least capable of supporting fish on the whole. This must have caused a leap in the desire to keep marines, and indeed the hobby from that time did open up and expand considerably.

Jumping forward a decade or so (great when you can time travel), look at us now! The under-gravel filter continued in great popularity for quite a while, but now that marine aquarium keeping was much more popular there were higher numbers of innovative minds wondering if they could ‘do it better’, and, of course, the commercial manufacturers started taking an interest, first in under-gravel equipment, and then in canister filter equipment and media suitable for marines. From there the hobby has leapt forward. There are now highly efficient protein skimmers (what an aid to water quality they are), biological trickle towers, denitrators, anti-phosphate reactors, water level top-up systems, calcium reactors etc. Seawater quality in the modern saltwater aquarium is unbelievably good compared to how it was not that long ago.

The very latest move has been to natural filtration techniques. Modern marine aquarists consider this to be the best, this is what nature does so it is considered that lead should be followed. The obvious example is ‘live’ rock, with all its bacteria, doing the work that the old under-gravel filter used to do but doing it so much better - used properly it even gets rid of the nitrate. Then there is the DSB (deep sand bed), the plenum (a raised DSB), further examples of nature’s way. Very good and successful they are too.

Looking at all the above it can be seen why filtration is such a hot topic, though it depends which angle the aquarist is coming from.

There are aquarists who may or may not have tried different filtration techniques, but now have one which has worked very well for them. Their fish and corals are a sight to marvel at. Water quality is very high, and without doubt they have done well. They will often argue vehemently that their filtration or filtration combination is best. Well, so it seems to them. Truth is, there could be another aquarist who uses different methods and gets just as good results. They’re not going to agree, more discussion!

Then there are the more serious aquarists. They too have marvellous aquariums, usually filtered by live rock and often linked to a sump with a DSB etc in. Maybe they use algae (Caulerpa) to enhance filtration. Maybe they use other means. What they do is keep up to date with new ideas and emerging technology that they may be able to use to enhance their systems. Of course, they will discuss and argue over the potential benefits or otherwise of new filtration equipment etc.

Then there are those leading aquarists who are not really content just to achieve a great captive reef display. They wonder if there is any new way to enhance their systems. There already is a display aquarium, of course, and an attached sump with a DSB and probably Caulerpa. Some attach another area that is in total darkness permanently, so that some sponges and other filtering life forms can develop. There are other experiments being done. One leading aquarist even pondered the possible beneficial qualities of Aiptasia anemones. These anemones usually make the average aquarist go on the offensive. But what is being considered is their filtration ability if they are allowed to multiply and grow. Any spread out of the designated area would be controlled. However, spread within the designated area would presumably be controlled by the supply of food. I can see aquarists arguing about that one!

All of this is an effort to make the display aquarium part of as natural a system as possible, where interference from the aquarist is minimised. It is my opinion that there will always need to be some interference and action by the aquarist as, no matter how big the aquarium system, compared to its wild counterpart it is very tiny.

So the marine aquarium hobby is advancing. From the inexperienced newcomer who is simply researching the systems and methods available right through to the pioneer who is adding another experimental area to an advanced system, there is discussion and argument. The absolute beginner can puzzle over and discuss filtration when one system appears, at least theoretically, to be ‘better’ than another. The very advanced aquarist or pioneer can argue in great technical depth about the merits of the latest potential advancement in filtration techniques. All those in the middle, the majority, can discuss and argue about just about any type of filtration in general.

It is a hot subject, filtration. It should be. It is an essential part of a successful, healthy, and vibrant aquarium. It is also the way forward, all this discussion, argument, and experimentation. It is also one of the things that make this hobby of ours so fascinating.

This is not an attempt to lay down railway lines for a converting aquarist to religiously follow, but hopefully a thought provoker that indicates some of what lies ahead.

Quite a number of freshwater aquarists are tempted to keep marines because they see a stunning aquarium somewhere, or they realize that keeping marines is not as difficult as they first thought, or they feel they have accumulated enough experience to make the change. Not all freshwater aquarists are the same of course. There are some really beautiful decorated freshwater aquariums about, and keeping one of these is as difficult as a reef aquarium.

Once the decision to change has been made, then the aquarist gets down to brass tacks. What next? What do I need? What can I use from the freshwater system?

The first owned item is, of course, the aquarium. The second the heater(s). The third, the canister filter.

The aquarium should be emptied and stripped. Once empty, it should be thoroughly rinsed in clean fresh water (tap water will do). Then it should be generally dried with clean cloths. There isn’t a need to use a sterilising agent as the aquarium is going to remain empty, dry and penetrated by air for a period, until the marine system is ready for assembly and use. If a sump has been in use this should receive the same treatment. If a sump has not been in use, then consideration should be given to having one. If it is decided to have one, have the aquarium drilled to receive the overflow plumbing.

The equipment needs to be obtained. A protein skimmer should be rated at around twice the net capacity of the aquarium system. The heaters are already available - if there is any doubt, or they have been in use for a long time, obtain new ones (two are best, rated at one half each of the required wattage). Circulation creation needs to be considered, by purchasing power heads, or an internal wave-maker, or both. A canister filter is already available, but it should be noted that this will be used for chemical and solids filtration only (bio-filtration is by other means).

Aquarium lighting needs some careful consideration. What does the aquarist intend to keep? It is likely that a fluorescent system is already owned, and this could be used on the marine system. However, the fluorescent tubes will need to be changed as the light spectrum will be incorrect. Actinic tubes combined with daylight types are required. Again, if the aquarist has a quite deep aquarium, and/or hard corals are to be kept, consideration should be given to metal halide lighting of the correct wattage and Kelvin rating.

It has already been stated that filtration will be other than a canister filter (it can be by canister filter(s) but these are not the modern recommended way). The filtration of choice is live rock. Live rock can be obtained as ‘base’ which is cheaper, and ‘premium’ or surface which costs more. The amount of rock is generally 1½ lbs for each gallon in the system. The rock can deal with ammonia, nitrite, and nitrate (provided it is not abused, it has limits). Further enhancing filtration can be placed in the aquarium, such as a deep sand bed (DSB). This DSB can also be placed in the sump. A Plenum (a raised DSB) is another alternative, particularly in the sump. Algae (Caulerpa) filtration can also be put to use in the sump.

If a DSB is to be put in the sump, then decorative sand in a fairly thin layer can be placed in the aquarium.

If there is to be a high calcium demand (hard corals) consideration can be given to a calcium reactor. In the larger aquarium additives can prove expensive and impractical.

An automatic top-up system could be put to use, again a good addition to the larger system. A small aquarium can use these devices but they are more of a luxury.

Now what of the seawater. The first need is sufficient dry sea salt. The second, at least after the initial mix, is a saltwater safe container for routine water changes.

Actually considering fish and/or corals hasn’t been undertaken yet, apart from the lighting requirement for corals.

So the freshwater aquarist has some equipment. He/she also has the experience of keeping an aquarium, and has no doubt done research on it. On the change to saltwater it is evident that a lot more research is required, not because the saltwater hobby is particularly difficult, but because it is particularly different.

One thing the freshwater aquarist probably has is patience. This patience will prove to be of immense value.