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.