These plastic filters, which can be hung on the side or back of the tank, have been available in the hobby for quite some time. They make excellent additions to other types of filters when such becomes necessary, but they are, in my experience with fish-only tanks, not efficient enough to run a decent reef tank. This makes sense because these filters were developed a long time ago, and not with the types of loads in mind that are typically found in reef tanks. Although such bioloads may appear less significant as the ones in fish-only tanks, they are in most cases not.

I have not been able to document any reference material where such filters were used successfully to operate reef tanks, nor do I have personal experience with running them on such tanks either. While we have tried a lot of filters at Thiel*Aqua*Tech, we have not yet run a reef on a plain box filter. Some hobbyists, however, report that they were successful in maintaining so-called tiny reefs.

Though very similar to box filters, BioMesh filters differ in one respect: they offer a far greater surface area for bacterial growth. Such is achieved by placing successive mesh filter plates inside the filter, plates through which all the water has to go before it can reenter the main water stream. The drawing of such a filter shows exactly what is happening in a clearer fashion. Although my company has carried two sizes of such filters for some time (1985 to 1988), we have discontinued doing so in 1989 because of a lack of hobbyist response.

BioMesh filters are extensively used in Germany and hobbyists report excellent results using them, even in large aquaria (Selzle, 1987). What is noteworthy, is that they naturally promote nitrate and phosphate reduction, without the use of any chemicals, fluids, nutrients or denitrators. Because demand was low, we no longer stock these filters, but still make them to order. Call Thiel*Aqua*Tech for details if you are interested. Pricewise these filters are in the same range as the better types of trickle filters, meaning they are not inexpensive, and you may well want to acquire a regular trickle filter instead.

3.2.3 CORNER OVERFLOW FILTERS:

These are, in reality, not really filters, but a means of bringing water down from the tank to the trickle filter, while at the same time pre-filtering that water mechanically. The filter usually consists of two parts, one that sits in the tank, and one that hangs over the lip of the tank and is connected to the top of the trickle filter. The part that sits in the aquarium has edges that are serrated. This prevents the fish from getting in the filter and ending up in the trickle filter on one hand, and ensures that the surface of the tank is strained of accumulated dirt, pieces and tufts of algae, slime, oily matter, etc. on the other.

By filling the larger part of the filter with an appropriate filtering medium, the unit can be made to perform as an excellent mechanical filter, thus preventing dirt and detritus from getting into the biological chamber. Filtering mechanically is especially important if the hobbyist uses DLS, a material that easily traps dirt and is widely used in trickle filters, mainly because it is inexpensive. It is, however, nowhere near as efficient as the plastic filtering media that are now available.

Corner overflow filters, or corner overflow boxes, should be cleaned very regularly. At least once a week is my recommendation. If such is not done, the filter may start restricting the water flow, which will reduce the overall efficiency of the filtration, while also posing a risk of water flowing over the tank and onto the floor, should the overflow box really get totally clogged.

Many variations on how to set up such filters exist. We will look into some of them later in this book. Overflow boxes are also called surface skimming filters in some literature. This describes their function more accurately, and the credit for coining the name should go to Mike Helton of Summit Aquatics in Fulton, Mo. Look for a unit that has an automatic restart feature, meaning that it will restart when the pumps come back on after a power outage. If you can find a self-priming overflow filter, such is an even better solution. Look too at the size of the outflow fitting. If you plan to run large amounts of water, make sure that the siphon has an outlet of at least 1 inch, preferably 1-1/2 inches.

Many materials can be placed in these filters to make them filter the aquarium water mechanically. Here are a few:

• Biomech, Efimech, EfiGrob (gross), filter floss, small biological balls, coarse foam pads and blocs, foam cartridges, removable foam cartridges, and so on. The choice is yours, as long as you remember that you must clean that filter regularly to prevent it from affecting the water quality by lowering the dissolved oxygen levels, and adding unwanted decay compounds to the tank.

Besides corner overflow siphons, hobbyists use corner overflow boxes, with a hole drilled through the bottom of the tank. Such an arrangement is even better of course, but must be installed when the tank is first set up. Retrofitting is only possible if the tank is taken down completely, which is not practical at all. Additionally, not everyone can have his or her tank drilled, for a variety of reasons. We will discuss this type of arrangement elsewhere in this book.

3.3 TRICKLE FILTRATION: GENERAL REMARKS

If biological filtration is such an important component of a well set up and well maintained aquarium, then surely, we will want the best filter money can buy to run our tank. We will want to maximize filtration efficiency, and we will want to do so on a continuous basis. This can only be achieved with a superior filter, and not with some arcane and obscure filter that is inexpensive and is advertised as the latest, or the best, or the newest, the most superior, and other such advertising gobbledygook.

What we want is a superior filter, from a company that has proven itself in the reef business, filled with an advanced biological filtration medium, constructed of the right materials and in a professional manner. To such a filter we can entrust the lives, well-being and growth of the fish, corals and invertebrates that we will be keeping in our tank.

In this case, paying a little more for a filter is certainly better, providing you choose a real advanced unit (and after reading this book, and others by Albert J. Thiel, you will know what to look for).

Several North American companies now offer such filters: Nautilus Aquatics (Canada), Summit Aquatics, Lifereef Systems, Oceanarium, World Class Aquarium, Thiel*Aqua*Tech's Platinum Series filters, and others. German units used to be at the cusp of technology; they no longer are! U.S. made filters now far out perform imported models, especially so since the introduction of the Platinum Series.

Nobody in the "aquarium hobby", however, can lay claim to having invented, or developed, that filter. Trickle filters existed and have been used for many years in the sewage (sewerage) treatment industry (I recently found a 1936 reference to them, in a book called American Sewerage Practices, given to me by Matthew Cammarata, co-owner of Thiel*Aqua*Tech).

We do need to give credit, though, to a German Pet Store owner and manufacturer of advanced aquarium systems: Mr. N. Nollman of Nollman Aquaristik in Sennestadt by Bielefeld, who modified sewage industry ammonia towers (large versions of trickle filters), to make them fit the purpose he intended them for: small freshwater and marine aquariums. He had small units available in the German aquarium trade, in glass, using clear balls with rods as a biological medium, long before anyone in the hobby was using such filters. In fact, I imported these filters into the USA in 1985, and sold them through my other company.

Because trickle filters have been around for so long in several other industries, mostly the sewerage industry, they have been improved upon, fine-tuned so to speak, over the years. The filters you see today, are an adaptation of sewerage industry ammonia towers, first down-sized, and then tailored and fashioned to better fit the conditions of an aquarium, in particular of a marine reef type aquarium, and freshwater plant tanks. Because of all the improvements made, they are now only distant cousins of the originals ones!

After modifying the filters to better suit aquarium requirements, Nollman, and many others after him, found that these filters performed extremely well: meaning the water quality of the effluent from these filters was superior to what they had obtained, in the past, when using different forms of filtration. This was encouraging of course, and led them to try to perfect these filters even more. As time went on, and as the filters appeared on the U.S. market, manufacturers, here, started producing such filters as well. Summit Aquatics is one such company.

Several years have gone by since the first trickle filters were brought into the country in 1985. Quite a few more modifications have been made since, culminating recently in a filter that includes equipment and many options that are recommended for use on marine reef aquariums, but incorporated in the same filter, meaning in the same space: the Platinum Series Filters from Thiel*Aqua*Tech, at this point in time the most advanced and most efficient filters available. It certainly is one you should consider if you are in the market for a trickle filter, not because my company makes them, but because this is the most advanced filter money can buy, and because it is priced very reasonably.

Trickle filters consist of several parts: a biological chamber, a sump, a drip plate, perhaps a carbon chamber, maybe a built-in protein skimmer, possibly a fine filter placed before the water enters the biological chamber, air inlets into the biological chamber, and so on. The more features the filter has, at least beneficial features, the better off you will be, and the less -overall- you will be spending on your filter. Indeed buying some options that you will probably need anyway, right from the start will save you money in the long run. As an analogy, just think of what it would cost you if you had to buy a car in spare parts!

Whether you buy a good filter, or a better one, depends largely on the features that the filter comes with. The more such features, usually the "better buy" the filter is. We will look at these features, and why you want them and need them, as we progress through this book. Looking through some hobby magazines recently, I counted advertisements for trickle filters, including the ones at the end in the small ads category;

53 different ones to be exact. Just about all of them obviously claim to be the best and the most efficient, and the only filter you will ever need. Caveat emptor. Beware, and study the offerings carefully before investing your good money in a filter that may not be for you, or that may not live up to its advertising claims.

It is unfortunate that, because of the present limited amount of knowledge that exists in the area of reef tank filtration, the too prevalent gullibility on the part of hobbyists, and the complete lack of verification of advertising claims on the part of hobby magazines, that small manufacturers, frequently not even legitimate ones, are able to make claims that are often misleading if not totally untrue, or unverifiable.

This is unfortunate because it costs the hobbyist money, and gives the trickle filter, in general, a reputation that it certainly does not deserve. Superior filters exist, several of them in fact. Buy your filter from a company that has been around for several years, or has a product line that is so wide in the reef part of the hobby that they obviously know what they are doing, and are serious about supporting the reef hobbyist.

Don't buy from people that sell on the basis of price alone. You are probably getting what you are paying for: meaning a cheap filter, that will not stand up to the task at hand. Look for a manual, and not a short and simple one at that, but a real thorough one (very desirable). The quality of the manual often is an indication of the type of company you are dealing with: is it made using a cheap stencil process, or is it printed? Telephone support is another feature you will need. Not necessarily an 800 line, but the ability for you to get hold of the manufacturer during the day time. You would be surprised how many of these small manufacturers actually hold other jobs, and only make filters at night, or on the weekend, making it most unlikely that they will want to talk to you to solve your problems. They want to dedicate the little time they have to building more filters (that they can't service either). Being able to talk to the manufacturer is an important criterion when selecting a filter. You will probably need to do so when you install the filter. It also comes in very handy to discuss the conditions of your tank, and what is happening in it, as time goes on. Do not underestimate this ability.

Do not overlook its importance. I hear complaints about not being able to reach such filter manufacturers frequently. We even receive phone calls from people who want information about filters they bought from other companies, but cannot get hold of. To help them, and in the interest of the hobby, we try to answer their questions anyway, even though they do not use our equipment.

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