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Much of the material in this section has been prepared specifically for this web-site or is already freely available elsewhere in the Internet.  Where we have included material from other sources we acknowledge that copyright remains with the original author. 

My Pond,  "What's what"

If you are a little confused by all the pipe work, then here is a description of what everything does.

1. This is the Nexus, the main component in the system. It is actually two filters in one.  In the centre a vortex chamber and stainless steel 'Answer' provide mechanical filtration of the water incoming from the pond at approx. 15,000 l/h. Here the solid material is removed before the water passes through the 'Answer' and  enters the outer biological chamber.  In the outer biological chamber the specially designed filter media is kept in a constant state of suspension by the injection of air at a rate of 6,500 l/h. The immense surface area of the hundreds of thousands of media particles combined with the oxygen rich water inside the chamber make this a very efficient Bio-filter indeed.  The water eventually returns to the pond via an underground 'Mid-water' return (6).  For ease of maintenance the waste sludge which is collected in the base of the vortex chamber can be flushed to the main sewer by opening the drain valve (7).   The base of the Bio Chamber can also be evacuated in a similar manner via it's drain valve (8).  You can judge the size of the Nexus if I tell you that the shed is 1.9M wide

2.  Secondary circulation pump.  In order to extend the capabilities of the filter system without exceeding the recommended flow rates in the Nexus system, a secondary filtration circuit is used. Water is drawn at 10,000 l/h from the bottom of the biological chamber by a specially constructed inlet manifold mounted below the air injection ring.  This is then passed through a 'Fines' filter (3) to remove small particles and improve clarity.   It then passes through a 170,000 BTU Heat Exchanger (4) before entering the  110 Watt twin chamber UV unit (5) and eventually returning to the Nexus's Bio Chamber.  On its journey through the Heat Exchanger its temperature is measured by the control computer to an accuracy of 0.1 deg C.  The computer uses this measurement to control the oil-fired boiler (9) in order to maintain the temperature of the pond to a programmed profile. The Red pressure vessel (10) is the expansion tank for the pressurised closed-loop heating system and is a necessary safety feature. 

The final item is the green hose (11) at the middle-left of the picture.  This is the 1/2" air supply to the Nexus's Bio Chamber and is powered by a 'Hi-Blow 110' industrial air pump.   If you are wondering what happened to the underground settlement chamber which I discussed earlier, it is under the floor of the shed just forward of the Nexus.  For inspection and servicing it is accessible via a trap-door just out-of-view at the bottom of the picture on the right-hand side.  A similar trap-door on the left-hand side gives access to the underground valve chamber.