An article by Rick Kitner that appeard in the KOI CARP magazine in June 2004.

THE WAY FORWARD IN FILTRATION

There are many different filters currently on the market, onefilter that is new to the UK but not new in its own right is theAquadyne. Amazingly the Aquadyne filter system that is currently causing quite a stir in the UK, has been around for nearly a decade and therefore is far from being a new pieceof equipment. It is in fact quite the opposite; it’s tried and tested worldwide.

The Aquadyne filter originated in the United States and was invented by a man called Greg Crane. With a background in Fluid Hydraulics Greg was a hobbyist who found the existing units to be very good initially but had serious long term clogging problems. He felt that there must be a better way. Eventually with the aid of research data supplied by Louisiana State University Sea Grant Program and many hours spent creating mock ups, scale models and prototypes the Aquadyne was finally born.

The one problem that he felt was essential to address was the problem of clogging due to convoluted and in many cases inaccessible pipework. It was these internal configurations that caused 99% of all the breakdowns that he had experienced. At the heart of the design was an ingenious central column that ran down the middle of the compact circular vessel that formed the body of the filter. It would be this piece of equipment that would supply and remove the water to the filter. All the control gear needed to backwash and clean the filter was attached to the top of this column thereby moving the internal mechanisms that had been designed within it. The internals were such a revolutionary design that a worldwide patent was immediately applied for, as everygood design needs to be protected.

Every filter should deliver clear and clean water. The Aquadyne did this but went beyond this simple remit. The water clarity produced by the Aquadyne was outstanding.Clarity of water is normally measured in how large the particles present within it are and these are known as microns. For example water containing particulate size ofsay 500 microns would basically have many large visible particles with sizes ranging from 1 to 500 microns. Water with 10 microns would only have almost invisible and tiny particles of up to 10 microns present. Therefore the bigger the micron size the cloudier the water. The Aquadyne had delivered an average micron size of below 50 and often a slow as 10. In real terms 10 micron clarity is clearer than many peoples tap water! This superb clarity was created by tightly packing the media within the filter resulting a slightly pressurised system which meant the water was forced through the mass of very fine silicon beads therefore effectively creating a simple but extremely effective 10 micron filter. The beads in question being so small around 3-4mm had, and still have, the highest surface area of any filter media. One cubic foot contains around 600,000 beads giving a huge surface area of over 400 square feet. In metric terms this converts to1,300 square metres of surface area per cubic metre nearly double that of any other plastic media and higher than many natural type medias.

With regards to clean water, once again the Aquadyne excelled due to its design, the filter had the ability to handle fantastically fast flow rates. On the larger models flow rates of over 6,000 gallons per hour were easily maintainable. The advantage of this was quite simple, the quicker the toxins i.e. ammonia and nitrite were removed from the pond, the better. Up until this point the benchmark figure of turning a pond over was every two hours as this was the best balance between speed of toxin removal and slowness of flow foro optimum mechanical settlement. It was not the ideal flowrate as filtering the pond only twelve times a day was way behind even the slowest basic goldfish aquarium, but it was the multi bay systems being used at the time that dictated this turnover rate. They could not handle the faster flows as it resulted in extremely cloudy water. Basically if the water was pumped at high speeds through these filters it would enter dirty and cloudy, be swirled around in each chamber and then pumped back into the pond biologically clean (i.e.no nitrite or ammonia) but still cloudy. To cope with a fastflow rate to achieve optimum biological filtration the filter would have to be huge, to enable efficient mechanical filtration. In real terms around the same size as the pond! With an Aquadyne filter suitable for a 12,000 gallon pond measuring only 1.15 Metres tall by 0.75 Metres wide, this was a massive improvement. One added benefit unexpectedly discovered was that the strong currents now present in the ponds were extremely beneficial in maintaining and developing strong muscle tone and therefore good bodyshape. Confirmation of this is that many Japanese breeders now add extra pumps to their ponds purely to create these beneficial currents.Seeing as the two main criteria were easily achieved, the only question the Aquadyne had to answer was ‘how easy is it to clean?’ The answer was simple ‘very easy’!

When the internal part of the Aquadyne was designed th ewhole issue of simple maintenance was just as important to ts creator, as the water quality it produced. After all who wants to spend time getting wet and dirty stripping downand washing out filters all the time? The way in which simple cleaning was achieved was to utilise the power that the high flow rate pumps made available. A large powerful 1.5 HP air blower was fitted, to blow vast amounts of air into the mass of floating media thereby loosening the tightly packed beads and dislodging the trapped particulate at the same time. Then a simple turn on the handle of the control gear and the flick of a switch followed by a wait if approximately two minutes while the media is washed by the main pond pump and job done! Not even the remotest chance of getting wet or dirty. To back the system up further and to make everything easier, a pressure gauge was fitted to the external control gear mounted on top of the central column. This was added to give a visual indicator of how dirty the filter was. As the particulate is trapped in the filter the pressure increases thereby giving warning that cleaning is necessary. One final addition was the introduction of a sight glass on the wasteside of the control gear for visual confirmation that the cleaning process is successful.The principle of biological filtration is quite simple, pass oxygenated water over media, whether it is Japanese matting, plastic media or gravel, bacteria will form and a filter bed will be established. All filters have to use this process. It is only the issue of how efficiently the filter does this and its ability to mechanically filter the water whilst doing so, where filters can differ greatly.Even though the Aquadyne filter has been around for anumber years and many thousands are now in use, it has not changed.

This is proof positive that the combination of Greg Cranes background in the Fluid Hydraulics field and his knowledge of Koi keeping, contributed hugely to the success of the filter.More than 10,000 Aquadynes have been sold around the world since its conception and amazingly only one Filter has ever been returned. With results like that and 5 star ratings from everyone that owns one, it is hardly surprising that the Aquadyne filter is making such a big impact in the UK.