[schildkoi]

Quote: It is impossible to know how many fish a biological filter can support, and how much fish waste and ammonia the biological filter can metabolize without knowing its SSA. SSA tells you how much nitrifying bacteria can live on the media - the biofilm layer as it is commonly referred. You don't know how much gasoline your car burns without knowing the Miles Per Gallon (MPG) - well, SSA is the same type of critical number to know." John R “Even knowing these factors you cannot adequately determine how much fish/waste a filter will metabolize unless you can also determine the ongoing cleanliness of the media, the flow rate and it ability to pass the nutrients in close enough proximity to the biofilm itself.” Steve C. How does one calculate this? What is the actual proximity and flow rate that the nutrients have to pass in order for the boifilm to act upon them? Let’s try an example. Say I have a 15K pond with 10 - 30” fish in it, feed at optimum levels at any given temp. Where do you begin and end in this example? Oh Yeh, No rock in this pond example. Jim

John Russel's explanation is a good starting place, in the perfect world and if all other contributing factors are perfect. There are also different levels of water quality (in this case ambient ammonia levels) that koi can survive within. These ambient levels are not measureable using our standard test kits, but in actuality much lower. Regardless of the grade of koi, the lower these levels, the lower the risks directly from and indirectly from the ammonia. So even at 100% conversion of what the bio filters are being fed, the rate of that feed will dictate what the ambient levels will be within the pond.

So, the bottom line is 100$ conversion of what is being fed and a rate that will reduce the ambient levels as much as possible within the pond. For that 100% conversion, the media must not only have an adequate surface area for the biofilm, it must remain clean 100% of the time and the ammonia molecules must pass within close enough proximity to the biofilm itself. These 2 factors are where the trade off for most filters begin since the proximity level is measured as a factor of micron(s). For the media iutself to be that close together, it also can create the propensity for clogging and thus the entrapment or settlement of ditrus on the surface area reducing the effectiveness through the starvation of the biofilm. This can be overcome a number of ways including the addition of excess media, and multi chamber bio chmabers to help add not only surface area but also iuncrease the likelihood of the molecules getting into close enoughh proximity. As mentioned previously, airation can help as well, creating internal current velocities that reduce the likelihood of settlement onto the media and also creating multiple passes through it. Fluidized systems utlizing air can accomplish both in a reduced area as well with the media itself also having a gre4ater likelihood through multiple passes of the molecules and the media into close enoough proximity.

Clear as mud, huh?

Steve