| NetPets® |
3.2 NEWER METHODS OF FILTRATION:
3.2.1 CANISTER FILTERS:
Canister filters, known to you by names such as Eheim, Fluval, Marineland, Atlantis, Lifeguard, Pep, and others, can be used on their own, as stand alone filtration, or in combination with other types of filtration. In fact, hobbyists often do the latter. Canister filters are frequently found in combination with undergravel filters, to supplement the efficiency of that filter, and/or to perform some other form of filtration, for example: chemical filtration, using Poly Filters, or activated carbon.
Canister filters are much more recent than other forms of filtration, having been pioneered in Germany, mainly by the Eheim Company. Nowadays, many brands are available, and in several sizes, for example Marineland's Magnum Series, making it possible to match up the size of the canister with the size of the aquarium on which it will be used. As the canister design was improved over the years, these filters can now be used for a variety of purposes: mechanical, chemical, biological, and (although I do not recommend such) as a combination of all three of those.
Canister filters have many uses, one of the more obvious ones being that canister filter can be used to supplement existing filtration in aquariums that carry a heavy load, where such additional biological and other filtration becomes necessary. Such a tank overload can have several reasons: (a) while going on vacation, a period during which the water quality may deteriorate because no water changes can be done, (b) while additional animals are placed in the tank, for instance because you have removed them from another one that you are working on, and © due to plain and simple overload because the hobbyist has placed too many animals in the tank, (d) and other reasons you can think of yourself perhaps.
One very important remark: clean all filters regularly, especially if they are functioning as mechanical filters (100 % or even partially). This is most important because any matter trapped in the filter will slowly decompose and affect the overall water quality. Place the filters in a convenient place. Thiel (1981) observes that the easier it is to get to or reach a filter, the more likely the hobbyist is to clean it. Keep that in mind when you set up your system. Do not place filters in odd places where they are hard to get to. Do things right the first time around. It takes less time, and is simpler than changing the system around at some later point in time, when the tank is already running and when any change you make will affect the appearance and behavior of all tank lifeforms, because any such changes will impact the chemistry of the water negatively.
You may not have all the answers, and you may have questions as to what exactly to do when setting up your filters. That is perfectly normal. Several courses of action are open to you: (a) read more about the subject in other hobby books, (b) get expert advice, ask questions to personnel of a local store, © talk to manufacturers, (d) talk to members of a local aquarium society. More than likely you will be using several of these options, which is the approach that I, too, recommend. Talk to people that you trust, either because their knowledge impresses you, or because you feel comfortable with what they have to say. Often the solutions to your problems will be simple.
Canister filters can be filled with a variety of materials. Be extremely careful when selecting these materials, making sure that all are totally saltwater safe, and will not leach any noxious compounds into the water. Saltwater is a very aggressive medium and far less compounds can be used in such water, than in fresh water. This is most important to keep in mind when selecting anything that will be placed in the tank, not just in the filters. Moreover, materials that may be all right to use in a saltwater fish-only tank, may not be suitable for a marine reef aquarium. Invertebrates are much more sensitive, and delicate, and may not be able to tolerate certain compounds that fish can deal with to some degree.
Activated carbon, often placed inside canister filters, can be the source of many troubles. Frequently, activated carbon of lesser quality (and a lot of it gets sold in the aquarium hobby under fancy names), will not remove as many compounds from the water as you expect, on one hand, and will leach phosphates into the water to boot. Phosphates will cause outbreaks of micro-algae to such an extent, that they will be very hard to control, let alone eradicate, even if one uses products to do so such as the ones sold by Thiel*Aqua*Tech and by Energy Savers Unlimited. Make sure that the activated carbon you buy is dull in appearance and not shiny. Shiny stuff is usually non-activated charcoal, a compound that is far less desirable to use and not nearly as good as superior quality activated carbon. Rinse the activated carbon before using it, and do so in warm water, as this will remove trapped gasses and open up the inner cavities of the activated carbon. Always place the carbon in such a way that water can flow through it freely. Bagging activated carbon is not always the best way to use it. Water may flow over the bag rather than through. Don't forget: water always seeks the path of least resistance.
To determine whether or not the carbon you have leaches phosphates into your tank's water, proceed as follows:
Note from the Author: at the time of rewriting this book (early 1990) I know of only three carbon brands that will not leach phosphates into your water: Thiel*Aqua*Tech's Reef Carbon, Marineland's Carbon, and the Cora brand from Germany. The latter is available, but not easy to find. More on activated carbon later in this book.
When it comes to canister filters, do not skimp on the quality. Get the best you can afford. Keep in mind that if you are going to rely on such a canister to perform filtration for you, it has to be good enough to do so on a continuous basis, 24 hours a day, day in day out, week after week. A flimsy little filter that you got real cheap won't live up to that requirement. Marineland's Magnum's and Eheim are excellent choices.
Filters, including canister filters, need to be cleaned regularly to prevent the trapped material from breaking down and lowering the water quality. Additionally, filters need to be cleaned to prevent them from getting so clogged that they fail to run properly. Whenever a filter performs a biological function in addition to some other form of filtration, each time you clean the filter you destroy a good part of the bacteria in the biological bed as well. This, too, lowers the water quality, and stresses the fish and other animals in the tank. This is the reason why I strongly recommend that all forms of filtration be segregated.
Lately, mixtures of activated carbon and special resins have appeared on the market. Such products combine the effects of the carbon with the deionization capability of the resins. Whether such is a product that you want to use shall have to be determined over time. Resins do not work well in saltwater. The reason is the heavy chloride and sodium ions, which interfere with the functioning of the resins, prevent the resins from absorbing the compounds that they should absorb, and do in fresh water. This would make such a product efficient only, if the carbon used is of excellent quality. The resins may not serve a great deal of purpose. However, if the carbon is of excellent quality, the product will certainly remove many noxious elements from the water. Keep in mind that activated carbon does not last forever. It needs to be changed from time to time. More frequently if your protein skimmer is undersized (Thiel, 1986).
How do you know when? Simple. Take a piece of white plastic. Make a faint yellow line (or several such lines) on the white plastic. Submerge the plastic in the aquarium, and hold on to it. Look at it from about 1, to ½ feet away. If you can still see the faint yellow line(s), your carbon is still good. If you cannot see the faint yellow line(s), your water has a slight yellow tinge which masks the difference between the white and the yellow of the piece of plastic. If your water is slightly yellow, your carbon needs to be changed. This is a simple and easy to perform test, and one you do not even have to buy. You can easily make it yourself. Any piece of white plastic will do. Permanent markers, found in stationery stores, make the faint yellow lines.
Although stand-alone canister filters can provide a fair amount of biological filtration, the amount of such filtration is small and not sufficient, in my experience, to run a small reef tank. When supplementing a reef setup with a trickle filter, canisters can serve a number of valuable functions. I use them myself for the following two purposes:
Ex-nitrate from Thiel Aqua Tech to keep nitrate levels low in my 135 gallon tank. The water is taken from the sump of the trickle filter, run through the canister and the Ex-nitrate, and then back to the sump of the trickle filter.
Note from the Author: These discs, which we will discuss more in detail later, are a proprietary product of Poly Bio Marine Inc. and are used by Thiel*Aqua*Tech, under special license, in their Platinum Series Trickle Filters, and also in canister filters. Both the Poly Filter and the molecular absorption discs are products that are far superior to activated carbon in 97 percent of the cases I tested. Only in one area is activated carbon still really necessary: the removal of residual ozone from the water coming out of protein skimmers and ozone reactors.
The bacterial beds in canister filters, and in undergravel filters as well for that matter, have a very short life expectancy when a power outage occurs. Within a matter of one to two hours, the filter can go partially or even totally anaerobic, especially if it has not been cleaned regularly, and if a lot of detritus is trapped inside the medium. Should the power come back on, say after 3 or 4 hours, and should this happen while you are absent, a great deal of damage can be done to your tank's lifeforms. Indeed, anaerobic filters produce very noxious by-products, which can create real havoc in the tank.
Special "trip" switches are available that prevent the pumps and canisters from restarting automatically when the power comes back on. These switches can only be reset manually. They help when the power has been out for a long time. But when the power outage is only for minutes or seconds, they are of no use, of course, as no damage to the filter beds would occur in such a short period of time. Additionally, your pumps would then stay off until you come back home, or happen to notice that they are not running.
Some hobbyists use canister filters filled with broken up pieces of coral to enhance, or maintain, the carbonate hardness of the water in the tank. This may work for some time, but not for very long, because as soon as the coral covers itself with slime and other detritus, the process stops. Moreover, at the high pH levels of marine tanks, the exchange does not work very well at all anyway (see also Spotte: _Seawater Aquariums, A Captive Environment_. John Wiley and Sons, Wiley InterScience. 1979). Similar observations have been reported by Hueckstedt (Kosmos, 1967), Thiel (Notes, 1986), and others.
Although the use of calcite, or broken pieces of coral, can be used meaningfully to increase, or maintain, the carbonate hardness, such must be done in conjunction with carbon dioxide. This process is explained later in this book under the heading Reactors: carbonate hardness.
Yet another use for canister filters is supplemental biological filtration when the canister is filled with one of the many plastic filtering materials now available: Techs, balls, Pax, cubes, packs, spheres, Super Techs, Plusses etc. This can be very beneficial if the tank is overloaded, or when more biological filtration becomes necessary due to, for instance, overfeeding, a skimmer that does not work properly, and so on.
| Back to Table of Contents | Back One Chapter | Top | Next Page |
 NetPets® Main Page |  The Fish Center |