| It is still happening. Massive amounts of | | | | This process is continuously repeated by virtue of |
| competition in the pond filter market and the | | | | the turbulence and agitation effect. The |
| battle for margin is resulting in pond keepers being | | | | contaminants in the circulating water is "bacteria |
| bombarded with techno-speak in an effort to | | | | food" (ammonia and nitrites dissolved in pond |
| increase sales of highly priced pond filters. | | | | water and which are metabolic products of the |
| The latest product I came across prompted me | | | | fish). This food is devoured quickly by hungry |
| to write this particular article although I've written | | | | bacteria coming into contact with the |
| about the subject many times. | | | | contaminated water. |
| My chemical engineering background has helped | | | | If there was no agitation the bacteria would tend |
| me greatly in separating fact from fiction for | | | | to become sluggish, trapped in a static |
| many pond products. | | | | environment, while waiting for new food to come |
| Over the last couple of years biofilters that use | | | | along. |
| highly agitated water chambers containing plastic | | | | The point I'm trying to make is to show that |
| cylinders have come to the fore. These filters are | | | | without agitation the water at the boundary of |
| quite expensive and they do perform well but are | | | | the plastic interface is essentially static or dead |
| over-engineered for most garden fish ponds. It is | | | | and the biological purification process is thus |
| also possible to get a similar effect on a DIY basis | | | | impeded. It is not stopped in such a static bed as |
| once the principles are understood. This article | | | | is the case for most pond filters, rather it is just |
| attempts to explain the principles. | | | | slowed down and is thus far less efficient. To |
| The reason why this type of pond filter works | | | | overcome this lack of efficiency most ordinary |
| well | | | | static filters are over-sized. |
| The reason has very little to do with any specific | | | | Just think of how a dish washer works or a |
| component. However it has much to do with the | | | | washing machine. Leave the dinner plates or dirty |
| biological process that takes place in any filter. | | | | clothes in a static pool of water and they never |
| These modern filters employ highly efficient | | | | come clean. Swish the water around and how |
| biological processes made possible by agitating the | | | | easily the dirt is removed. This is a simple |
| biofilter media (the best known is called Kaldnes) in | | | | mechanical rather than a biological process |
| the circulating pond water. By reproducing this | | | | however but it illustrates the principle of boundary |
| process in any box type of filter much improved | | | | layer dynamics well enough. |
| results can be obtained using almost any small bits | | | | This is what you need to know ... All Biofilters of |
| of plastic that can be agitated. The plastic surface | | | | any kind will perform better in an agitated state. |
| is the substrate onto which bacteria cling. They will | | | | And the Second Major Secret Is ... Oxygen |
| cling to any surface. | | | | contained in circulating pond water. |
| Now here's one of the 2 major secrets ... | | | | Those millions and millions of purifying bacteria in |
| If the mass of water holding the Kaldnes can be | | | | any pond filter system need Oxygen, Food and a |
| agitated then the Kaldnes will remain in suspension. | | | | Flush to remove products of biological purification |
| Such a state of suspension is perfect for | | | | to do a good job. Just like we do. |
| effective bio filtration of any kind. | | | | In a well agitated system even without extra |
| The turbulent mixing of biomedia within a polluted | | | | aeration pond keepers will see major |
| body of water will allow bacteria and contaminants | | | | improvements in pond filter efficiency. When you |
| to come in very close proximity with each other | | | | add extra air to keep water saturated with |
| continuously. This means bacteria can break down | | | | oxygen then the bacteria are at their most |
| toxins contained in the contaminated water | | | | virulent. They mop up the impurities (ammonia |
| (ammonia and nitrites) and have the resulting toxic | | | | and nitrites) in no time at all and the "Flush" from |
| chemicals removed instantly at the water | | | | agitation allows them to start all over again with |
| interface with the substrate. In other words old | | | | fresh oxygen, fresh food and clean water. |
| water now purified by bacteria on the substrate is | | | | These are the keys to great pond filtration. |
| flushed away and is immediately replaced by | | | | One of the modern filters uses a venturi system |
| contaminated water. This new arrival of | | | | to add oxygen and create agitation at the same |
| contaminated water is then purified by the | | | | time. You can do the same ... a venturi costs a |
| purifying bacteria before once again moving away | | | | couple of Dollars. |
| back into the body of the agitated water mass. | | | | |