Because of the nature of the filtering that an aquarium requires - especially reef aquariums -, other media besides just biological types need to be relied on to purify the water in the tank. Specifically, activated carbon and polymer-type media are the more commonly used ones. Both are quite popular nowadays, especially in fish-only tanks.

In reef aquariums, however, the story is slightly different and hobbyists should be very careful as to what type of carbon, for instance, is actually used. We will be dealing with these media, and their relative merits, benefits and drawbacks, more in detail in a later chapter. Suffice it to say, at this stage, that if you are planning on using either of them, you will need space in the tank, or in the trickle filter, or its sump, to place these media so you can use them properly and make them work efficiently for you.

Activated carbon definitely needs to be used if you are also injecting ozone into a protein skimmer, or an ozone reaction chamber (see later for more details). Polymer type filters, such as the Poly Filters, or Molecular absorption discs from Poly Bio Marine Inc., are definitely needed in a reef tank to remove many of the undesirable compounds that other forms of filtration do not remove. By other forms of filtration we mean biological, mechanical, and foam fractionation also called protein skimming. Having spaces, or compartments, already built into the filter where such media can be placed will save you a lot of time later on, and will make it easier for you to add them to your system without having to improvise.

Remember it is not just important that you use such media, it is also as important that you use them in the right manner: meaning the water must flow through the medium evenly and thoroughly, not just over the medium, or by the medium.

If the filter that you now own does not have such chambers, or compartments, you may wish to add them yourself by cementing two or more acrylic plates inside the sump between which you can wedge activated carbon or Poly Filters. Alternatively, you can place the media in a canister filter, for example a strong Marineland, or similar filter, taking water to run it from the sump of the trickle filter and returning it there. In this manner the operation of the canister will not interfere with the functioning of the trickle filter, and will not affect the water level of the sump either. I have used both the Magnum 330 and the Eheim 2217 canisters to this effect. Both work very well.

Built-in protein skimmers, or foam fractionators, are not a common feature included in the trickle filters that are nowadays on the market. Most of the skimmers offered for sale are, in fact, not even venturi operated, but columnar. Venturi valves are a special valve, built in such a way, that as water passes through it, forcefully, the valve sucks in outside air because of a differential pressure created inside the valve (right after the air inlet hole).

It is not important that you understand why they work, just be aware of the fact that venturi operated skimmers are more efficient than columnar skimmers (Guido Hueckstedt 1967, Aquarien Chemie, Kosmos). More on protein skimmers, both columnar and venturi, themselves in a later chapter.

Owning a trickle filter that is equipped with a built-in venturi skimmer is a definite advantage. Not only will you have a very efficient skimmer, but you will also save yourself a substantial amount of money by not having to buy the skimmer as a separate item. Indeed, good skimmers can be quite pricey, especially if you research available skimmers somewhat, and buy a real good unit properly sized for your aquarium. In a later chapter you will find a checklist that you can fill out to select the right skimmer for your tank. It is simple and straight forward and will let you end up with the properly configured unit that your tank requires based on the load, type of filtration, type of aquarium, whether you use ozone or not, and many other such variables.

Besides, some could not even be operated with ozone at all because several of their parts were not ozone resistant. (Note: make sure that any skimmer you buy can be operated with ozone! Ask the question specifically to the manufacturer, or main importer. Ask them for how long they will guarantee their skimmer against breakdown due to ozone.

Totally ozone resistant skimmers can be built as well, meaning skimmers that can resist ozone for greater lengths of time, e.g. several years. The price of such a skimmer would however be about three to four as much as the price of a regular skimmer.

All Platinum Series filters contain a venturi operated and correctly sized protein skimmer that can be further improved upon by ordering a molded, rather than manual, venturi, for a nominal supplement. These skimmers are built right into the sump of the filter, and do not require extra space since they are part of the footprint of the filter itself. Right after the skimmer chamber, in the area where the water exits, another chamber is already built that can be filled with activated carbon, to allow those hobbyists using ozone to remove residual O3, or to allow for the addition of Poly Filters or molecular absorption discs from Poly Bio Marine Inc. for the much required chemical filtration (for more on chemical filtration see later chapters) that your reef aquarium needs.

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