| NetPets® |
3.4 ADVANCED TRICKLE FILTERS
3.4.1 GENERAL REMARKS
Advanced trickle filters are nothing more than basic trickle filters
Advanced trickle filters, such as the ones just described, may not cost much more money than regular trickle filters because the companies that make them usually sell enough of these filters to be able to keep the price down to a reasonable figure. It is really incumbent upon the hobbyist to shop around, and select such a filter from the many offerings that are now advertised in hobby magazines, keeping the remarks made earlier about advertising claims in mind.
The choice is large and yours. Don't buy the first filter you look at, ask lots of questions about the one you are interested in. Try to get a copy of the manual in advance (even if you have to pay for it. Ask if the cost will be refunded if you end up buying the filter). Get exact measurements so you can make sure it will fit underneath your tank. In short, get as much information as you can before you actually buy. The more you know, the more educated a consumer you are, and the better a decision you are likely to make. This is a crucial buying decision, take your time. Do not buy impulsively, but check several filters out systematically and in detail. Make sure as well that the filter comes with a warranty.
3.4.2 TRICKLE FILTER BIOLOGICAL MEDIA:
At about the same time as you decide on which filter to buy, you will have to select a medium for biological filtration. Many such media are now offered for sale. Here are just a few (some of these names are trademarks of their respective companies):
| >BioMech by Kordon | >Jaeger Tri-Packs |
| >Bio Spheres | >Norton Rings |
| >Pall Rings | >Raschig Rings |
| >Flex Rings | >Matrix I |
| >Matrix II | >Bio Techs |
| >Super Techs | >Cut PVC pipe |
| >Shotgun wadding | >Plastic Haircurlers |
| >BioBale | >Balls |
| >DLS material | >Crushed Coral pieces |
| >Broken up dead coral | >Biopax |
| >Bio Blocs | >Bio Cubes |
| >Mini Balls | >Lampacs |
| >Impacs | >Plastic netting |
| >and still others. The choice is very large and also very confusing to many hobbyists. | |
All are touted as the one you should use. All claim to have very large amounts of surface area, larger in fact than the original balls that were introduced in 1985. How these companies arrived at the surface area claimed is a mystery. It is so to me, and to many people knowledgeable with how such a surface area is calculated. Rather than write on the relative merits of the claimed surface areas, however, let's look at what the medium that you select should have as qualities and features:
(1) it should offer as large a surface area as possible for beneficial bacteria to grow on and
(2) it should not easily trap dirt, detritus, algal debris, etc. and
(3) it should allow for good gas exchanges, especially oxygen.
What does this all mean? Let's look at each of these features one at a time, and explain why they are required and what their relative benefits are:
(1) large surface area: the larger the surface area, the more Nitrosomonas and Nitrobacter bacteria can grow in the filter. Within reason though. Only as many bacteria will be present in the filter as there are food & nutrients for them to survive on. If, for argument's sake, only enough nutrients are available for 108 bacteria to survive on, that's all there will be in terms of numbers of bacteria. There cannot be more, because there are no nutrients for them to survive on. Providing space for twice that amount of bacteria does, therefore, not make sense.
Some margin is necessary because the amount of by-products that the bacteria need to process varies over time and can increase, for instance when you add another fish or invertebrate. More space needs to be available, therefore, to accommodate the additional amount of Nitrosomonas and Nitrobacter that will populate the filter from time to time.
How much space do the bacteria really need? Because of their micronic size, very little. It is usually an accepted rule, in my circles anyway, that the following surface areas suffice per gallon of water in a system, of the type mentioned below (I mean true surface area, which is not necessarily what the advertising claims state):
These numbers are a guideline and should be used only as such. Before applying them to any material that you plan to use, you must first make sure that you know the true surface area of the medium.
For example: blue hedgehog-like balls (also available in clear natural color from several other companies) have a surface area of 80.000 square centimeters per 20 liters of balls (figures taken from the brochure of the distributor). Converted to square feet this is somewhat slightly higher than 16 square feet per gallon volume (which itself is somewhere between 75 and 80 of the balls, depending on the container used).
If you were to use these balls on a 100 gallon tank with a medium to heavy load, using an average of the guidelines above for heavy load, you would need 100 x 2-1/4 = 225 square feet of surface area for bacteria to grow on. 225: 16 = +/- 14.00 gallons of the balls, or slightly more than 14 percent of the water content of the tank.
Because I have seen claims for those balls' surface area as large as 23 square feet per gallon, you could also conclude that you only need 225: 23 = +/- 10.00 gallons of the balls, or about 10 percent of the water content of the tank. "You" must be the judge, and decide what the true surface area is, and then select how much volume you will need.
The example given here is not meant to place these balls in a negative light, to the contrary, but is used as an illustration of how confusing the decision of how much material you really need can be. You should make these calculations for any of the materials you decide on, but only after you have understood the total picture. Indeed, surface area is only one of the qualities that a good trickle filter biological filtering material should have.
Looking at another example, using Super Techs, on the same 100 gallon aquarium, gives the following figures: 225 square feet of surface area needed, divided by 29 (surface area of one gallon of Super Techs) = 7.75 gallons, or roughly 8 percent of the water content of the system.
If one now multiplies the number of gallons needed by the cost of the media looked at, one gets a total cost for the media that will go in the filter. Such is, in my opinion, the right way to look at the media that are available. How much of it do you need? How much does it cost per gallon? What is your best buy?
(2) Does not trap dirt: the reason for this, is not to prevent the space available for bacteria from being reduced, because it is now taken up by dirt. The reason this is mentioned, is because several hobbyists had brought it up as a question during phone conversations I have had with them at Thiel Aqua Tech. The real reason is much subtler: dirt that gets trapped in the medium (a) prevents water from flowing through the medium evenly, and (b) results in decay.
Decay occurs because the debris, dirt, detritus (call it what you want), will start decomposing in the presence of oxygen. Decomposition brings about two undesirable results: (a) it reduces the amount of oxygen in the water, the so-called dissolved oxygen level, and (b) it adds noxious decomposition by-products to the water. Both these actions result in a lowered water quality, which in turn increases the stress on the animals and may lead to outbreaks of disease. Even if no disease breaks out, lowered water quality and increased stress lead to a tank that does not look as good at it could, and should.
For a medium not to trap dirt, it must be made in such a way, that whatever dirt flows through the chamber in which the medium is placed, such dirt will gradually pass through the medium and end up in the bottom of the filter: the so-called sump. Media that are tight in their structure, for example DLS, haircurlers, shotgun wadding, cut up PVC, and like materials, do not fit this criterion, and should be avoided.
They may perform well for a while, but they will invariably cause problems after a short amount of time. The latter will vary depending on how well the water that goes into the biological chamber is pre-filtered. The better it is, the longer the medium will perform. After 8 to 10 months, however, even the best pre-filtered water will have created several areas that are full of accumulated small debris in all these materials. Many hobbyists report problems with DLS after only 6 months.
Surface area and not trapping dirt (having enough void space) must, therefore, be combined when looking at media for trickle filters. They both are important and they both need to have your attention during the selection process. Of course they are somewhat contradictory, because the more void space the less surface, and vice-versa. The right balance between the two, combined with the third criterion, will narrow your choice of biological filtering media down even further.
(3) Gaseous exchanges: since we already know that the biological filter is a very aerobic filter, one where oxygen is needed in large quantities, it should be obvious that the medium that you will use in that filter, needs to allow for efficient and maximum transfer of the oxygen in the air that we are blowing into the biological chamber, into the water that passes through that same chamber in streams and drops. This is important both for the activity level of the bacteria, and for the dissolved oxygen levels in the water. More oxygen in the water is beneficial because it reduces stress on the fish. Reduced stress is paramount in avoiding disease, especially parasitic disease, and having a tank that looks at its best. Newer media, developed with increase gaseous exchanges in mind will be the media of the future; second generation media so to speak.
3.4.3 AERATION OF THE BIOLOGICAL CHAMBER:
We have alluded to the need to aerate the biological chamber several times already. We have done so because it is an important factor that all hobbyists who run trickle filters must deal with and understand. The bacteria that grow in the biological chamber are aerobic bacteria. Aerobic bacteria need oxygen. Providing large amounts of oxygen to these bacteria enhances the efficiency of your filter. Not providing oxygen means that you are running your filter at a lower level of efficiency. This is somewhat similar to always driving a car in third gear as the highest gear when, in fact, that car has five. Such would not be a very efficient use of that car, would it now? The same applies to your filter.
You cannot blow too much air into the chamber. Use a good quality strong air pump. I personally use and have used Wisa 200 and Wisa 300 pumps for many years, and I highly recommend them. The air must be blown inside the biological chamber itself. Not in the water right underneath that chamber. Some pictures that I have seen, and some drawings in other books, may lead you to believe that you should blow the air in the water underneath the biological chamber. Such is not correct. You must blow the air directly into the chamber where the media is. That is where the best gaseous exchanges will take place.
It has even been demonstrated that varying the amount of air that is blown into the filter can alter your redox potential (more on the latter later in this book). G. Bepko (1988) in tests on a 100 gallon marine reef system equipped with a 10 gallon trickle filter filled with blue biological balls, demonstrated that when he cut off the air his redox potential, as measured with a Sanders controller and electrode, went down significantly after about 40 minutes, and stayed depressed until about 30 minutes after the air had been switched on again. I personally verified this on my own tank and found results close to his.
An even distribution of the air throughout the biological chamber may require more than one inlet, especially on larger filters. All Platinum Series filters that we build have 2 such inlets standard, regardless of size. This ensures that the air is distributed all over the biological chamber, for maximum efficiency. If your filter, or the one you are contemplating, does not have such an air inlet, you should either add it yourself, or look for another filter.
It is not unusual for certain kinds of resellers to downtalk products they do not carry, and try to sell you something they do have on the shelves. You should be aware of this. It may not be as common as certain sources suggest, but it does happen. Again, beware, and know exactly what you want and why you need it. The more educated a consumer you are, the better a buyer you will be, and the less likely you are to end up with merchandise that you do not need, or that does not serve the purpose you intended it for.
| Back to Table of Contents | Back One Chapter | Top | Next Page |
 NetPets® Main Page |  The Fish Center |