SuperActiFlo is our moving bed media of choice.
A moving bed is a simple concept to understand. What happens is very simply you have a vessel, such as a gULP in which you mix water and SuperActiFlo. Then you add bubbles via an airpump to the bottom of the gULP in an even distribution.
SuperActiFlo is very slightly buoyant. Without the bubbles in the filter, it floats, just below the surface. But with the addition of bubbles the media begins to move with the turbulence created by the bubbles moving upwards to the surface. All the individual media elements begin to churn around randomly within the filter.
This has several very important effects. The media is now operating as a moving bed - so called because all the individual SuperActiFlo components are moving chaotically within the filter environment. If you painted one individual SuperActiFlo element a different colour and watched it's movements within the bed you would see that over time this busy individual will make its way to all parts of the filter eventually.
What this means is that the moving bed is effectively very well mixed. This is super important to understand because when you have a very well mixed environment it means that incoming ammonia also becomes very well mixed. The more mixed things become the more opportunity there is for ammonia to come into contact with bacteria living in the bio film growing on the SuperActiFlo media.
The result is that you get massively more ammonia reaction taking place within a moving bed than with any other static media. The difference can easily be 10 times as much! Within a moving bed you get absolutely none of the water tracking phenomena that one gets in static beds - this is the phenomenon where water enters a filter and heads directly towards the exit in a straight line, by passing up to 85% of the filter in the process.
So SuperActiFlo is extremely efficient. Hence you can use a lot less of it and you can have smaller filters. But it has other important benefits too.
Because SuperActiFlo is agitated by air bubbles the entire churning moving bed is kept saturated with oxygen at all times. We know that the ammonia conversion process is extremely oxygen intensive - you need 4.3 times as much oxygen per unit of ammonia converted. So importantly the bacteria in the SuperActiFlo moving bed are kept fed with oxygen at all times, and the water leaving the filter returning back to the pond is oxygen rich still. We all know the importance of keeping our pond water as oxygen saturated as possible - it is a critical success factor of Koi pond keeping.
But wait! There's more!
SuperActiFlo is self cleaning. The individual elements cannot help but get involved with each other. As the media tumbles and churns within the bed it continually scrapes against the sides of the filter and of course against each other (it's made of sturdy plastic which will last for decades so don't worry about it 'wearing out'). As it rubs against itself any bio film growing on the outside of the media is scraped off and the bio film is continually trying to re-establish itself on the outside of the media. Trying to develop new bio film is an energy intensive process meaning that the bacteria are hungrier as they have to work harder. So they convert more ammonia.
SuperActiFlo is unique amongst media in this regard. Only a moving bed is able to produce a continuously replenishing bio film environment. Meanwhile within the protected inner surfaces of the media the bio film and bacterial colonies can continue the normal life cycle.
Of course any bio media will produce waste via dead bio film etc. In the case of a gULP filter this settles out into the sump and simply 5 second flush once a week will purge any small build up of detritus. Other than that SuperActiFlo requires zero maintenance. Zero. Zip. It works better the more you leave it alone in fact!