Biological Media School


Your goal is to provide a healthy, clean, environment for your fish. Every pond, hatchery and fish tank requires a filter of some sort. There are many types and styles to choose from however for most of us there are basically two primary designs when it comes to biological filters. Moving Bed Filter and Fixed Bed Filters (Trickling or Static Filters).


I've been in the mass transfer industry for more than 13 years, and whether you’re distilling crude oil (or whiskey) or designing a biological filter there are basic principles that are constant in both applications.  You want to increase the amount of contacting between two mediums. For crude oil the goal is to increase the contacting of gas and liquid, to separate the components based on their volatility. This is generally accomplished using a column filled with tower packing or distillation trays. In a moving bed, or fixed bed, biological filter you want to increase the contacting of the "dirty" water with the biological covered media. This interaction allows the biological growth to remove, or "eat", the waste components in the water that's harmful to your fish.


Now that we've established what we want to do, we need to devise a way to make this happen in an economical method. This is actually a pretty simple step; get as much interaction between the biological growth and water as possible in the smallest possible area (filter). The best way to do this is use a media with the highest possible surface area so you can use the smallest filter housing as possible. However if this was all there was to it everyone would use a small sand filter (extremely high surface area), but there's a little more to it than that. The interaction between the media and water must have good hydraulics to ensure required removal happens. It’s an essential part of the process to control the biological growth or the media will become completely covered and reduce the amount of contacting area, thus reducing the effectiveness of your filter.


What makes a GREAT moving bed biological media?




















1: Surface Area


This is the single most important consideration in choosing a biological media, although not the only consideration. Why is surface area important? This is the measure of contact between the water being treated and the biological growth that cleans the water. The more area you have the small the filter will to be. However the surface area of the media must be a "usable" surface area. This means that the media must maintain a biofilm that is consistent and does not block the surface area of the media as it grows. For example; a sponge has a lot of surface area however once the biofilm starts to grow it fills the voids rendering much of the surface area unusable.


Here at Smoky Mountain Bio Media our media has some of the highest surface areas of any moving bed bio medias on the market, the BioFLO 9, BioFLO 40, BioFLO 25, BioFLO 15 and BioBLOCKS, ALL exhibit the highest usable surface areas for whatever type of filter system you design. In addition to our high surface area the media is engineered to optimize the biofilm on the media, making our media the most efficient on the market.


Continue on to get the rest of the story.....


2: Hydraulics


The ability for the water and biological growth to interact with each other is of the upmost importance. Smoky Mountain Bio Media's filter media is engineered such that all of our surface area will be utilized for biological growth and transfer of water, thus making it one of the most efficient, if not the most efficient, medias in the market. All of our filter media is designed such that the water will freely move around and through the media ensuring maximum transfer between the biological film and the water. It's important to make the media as uniform as possible to ensure good hydraulics to ensure as much water as possible will come in contact with the biological growth. Bio Balls and sponge type medias may promote a lot of surface area but much of this surface area is located on the inside of the product where there is little interaction between the water flow and biological film. Not to mention that the biofilm will easily cover the stated surface are reducing the effective surface area even further. Hydraulic consideration is commonly over looked, but it's extremely important in a bio media.


3. Biological Growth


The biological growth is what the filter is all about, it's what must take place for your filter to work. Along with the two points above we can put this discussion to rest. You've narrowed your results down to a few different types of a high surface area media, you've kept in mind that we need good hydraulic mixing between the media and the water. Now let's discuss biological growth and how to keep in under control. The bio media starts to become covered with biological growth but how does it know when to stop? It's easy, it doesn't. This is where items one and two work together.


Moving bed filter: As the media is being moved around in the filter the pieces of media begin to collide with one another. These collisions release some of the biological growth and keep the media relatively clean. We don't want the media completely clean though, the goal is keep a thin a layer as possible over the entire piece of media. This will ensure the we don't lose any of the surface do to biological over growth, or unutilized areas where biological growth is not present. Your task now is to adjust your air or water flow to move the media around to optimize this. There are several websites that will provide you with guidelines however you should adjust your flows to optimize your filter.


3. Material Selection:


Material selection is very important. Generally there are two primary materials considered for plastic biological carrier media PP and PE. Either one is acceptable for water systems, biological growth take well on these material, and it's relatively cheap, so it's a good choice. Beyond that it's important to remember that materials not made equally. Here at Smoky Mountain Bio Media our plastic material comes from reputable suppliers only; global companies like INEOS, DOW, DuPont...ect, this ensures we only receive the highest quality material with essentially no impurities. In addition we generally only use virgin grade material that conforms to NSF drinking water quality standards! Why is this important? Non certified material can contain material that can be toxic to your fish and reduce the effectiveness of your biological growth on the media. Many of the companies who sell bio media do not consider this and buy their material from Chinese manufactures not knowing who supplied the raw material.


Most of our competitors don't even engineer the media they sell! That's not the case at Smoky Mountain Bio Media!