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Frequently Asked Questions

• The pump could be too powerful, so the Nexus+ is being emptied before the pond refills it by gravity.

• There could be a blockage in the transfer port between the inner and chamber and the outer chamber. You need to back flush it. You can download the instructions to backflush here.

• The Eazy needs cleaning. Or the Eazy’s steel screen needs cleaning. Beware of sharp edges!

Maximum recommended flow on the 220 is 10,000lph and the 320 is 13,000lph, however suggested flow rates are lower. Slower is better for fine removal and clearer water. Aim to turn over your pond volume every two to three hours. The Evolution Aqua Varipump range are adjustable, and consume less energy when you turn them down.

Yes, it can easily be adapted to either filtration method by simply swapping the supplied rubber boots.

The Nexus 220+ comes with 18 litres of K1 Micro in the Eazy (inner chamber,) and 50 litres of K+Media in the outer chamber.

The Nexus 320+ comes with 20 litres of K1 Micro in the Eazy (inner chamber,) and 100 litres of K+Media in the outer chamber.

For older models, the 300 and 310 contained 40 litres of K1 in the Eazy, and 30 litres for the 200 and 210.

Don’t change the amount of media in the Eazy as this affects particle capture, and ease of cleaning. The amount of media in the outer chamber can be increased however by up to 150 litres in total in the 220 and 300 litres in the 320 models.

Only increase the amount of media in the outer chambers for heavy stocking and heavy feeding. Note that if the total volume of media is increased in a newly set up filter it will take longer to mature, as there is more surface area for bacteria to colonise and the biofilm will be more thinly spread.

Media can be purchased from your Evolution Aqua dealer.

Yes, it powers the moving bed biological filter and is also vital to the cleaning process. You need an Evolution Aqua Air Pump 75 for a Nexus 220 and an Air Pump 95 for a Nexus 320. If you increase the amount of media in the outer chamber you may well need a more powerful airpump.

The correct size airpump to enable the filter media to move is detailed in the below:

  • 50 - 75 litres = Use an Air Pump 75
  • 75 - 100 litres = Use an Air Pump 95
  • 100 - 150 litres = Use an Air Pump 130
  • 150 - 300 litres = Use an Air Pump 150

The return pipe is 40.5cm long in the 220 and 46cm long in the 320. This is a length of 4" pressure pipe which is factory fitted during production to the return chamber of the Nexus and sets the level of the water in the Nexus. It is removed when using the Nexus in a gravity fed pond. This can be quite difficult to retro fit as the hole is quite tight, you may find it easier using 110mm soil pipe as this has a slightly smaller outer diameter.

Nexus 220+

  • Total volume of water 510 litres / 112 UK gallons / 135 US gallons
  • Outer chamber 405 litres / 89 UK gallons / 107 US gallons
  • Inner chamber 105 litres / 23 UK gallons / 28 US gallons

Nexus 320+

  • Total volume of water 840 litres / 185 UK gallons / 222 US gallons
  • Outer chamber 635 litres / 140 UK gallons / 168 US gallons
  • Inner chamber 205 litres / 45 UK gallons / 54 US gallons

Remove the outside union on the waste ball valve, open the valve, if no water pours out the blockage is under the Nexus, carefully push a suitable stick (such as a cane) and release the blockage, you can also remove the Eazy and access the pipe from the 1.5" hole in the bottom of the Nexus inner chamber.

  • Check if the inlet valve is being obstructed.
  • Check if the yellow light is illuminated. If light is not illuminated after 3 minutes, initiate a manual clean to check operation.
  • Check the wiring is correctly installed. Seek advice from a suitably qualified electrician if in doubt.
  • Check the mains connection to the control box. Seek advice from a suitably qualified electrician if in doubt.
  • Check the fuses inside the control box. These are located alongside the timer blocks within their own hinged compartments. The fuses are all standard glass fuses; 10 Amp, 5 Amp, 2 Amp, 2 Amp from left to right.
  • Check air pump is running.
  • Check the air line is correctly installed from the air pump to the air control box.
  • Check cleaning cycle is operational. If inlet valve is closed, air will only divert once inlet valve is open.
  • Check air valve control box is connected correctly.

You can identify the spare part you need in the Nexus manual, the spare parts list is located on page 29. To view the manual, click here. Alternatively, you can identify the spare part you need from the image below.

Nexus Spare Parts

The K+Media in normal conditions becomes semi-buoyant within 48 hours. However, the K1 Micro (only in the Eazy) takes longer to absorb water. This can take up to one week.

The reasons for this could be one of the following:

  • The air pump is not powerful enough (see Air Pump Recommendation on page 4)
  • There isn’t enough water in the Nexus – check that you used the cleaning pipe to maintain the level on a pump fed system.
  • Check all air fittings and air line for leaks and blockages.
  • Please ensure that there is no more than 18 litres of K1 Micro in the Eazy. If the media is not moving well enough you can take a few small handfuls out if needed

A typical filter can take approximately 8 weeks to mature. During this time Ammonia and Nitrite levels will rise and fall. This process can be accelerated by using PUREPOND. If you still experience Ammonia and Nitrite readings after this period of time, check the following:

  • Nexus is adequately sized for the pond.
  • Check flow rate is correct - ensure the pond water is being turned over through the Nexus every 2 to 3 hours without exceeding the maximum flow of the unit. • Check chlorine levels of tap water and pond water - ensure a dechlorinator is used on mains water top ups.
  • Ensure pond water pH is above 7. If it is above pH 7 keep it as stable as possible.
  • Check feeding and stocking rates of pond
  • It is important that the Eazy is flushed a minimum of 2 times during cleaning. This ensures that all the debris collected is flushed out to waste. If the unit is only cleaned once some debris can be returned to the pond, clouding the water. Flush the unit 2 to 3 times as per the cleaning instructions and water clarity should be restored within 3 to 7 days.
  • Check your pond food is of a good quality and it is not discolouring your water. If it is please use Evolution Aqua’s range of pond food.
  • Check that the evoUV is working and the bulb has not exceeded its 9000 hours lifespan. It is recommended to change a UV-C bulb at the start of each pond season.
  • Check that you turned your circulating pump off and that you have used the cleaning pipe, so that the dirt in the K1 Micro hasn’t returned to the pond.
  • Check that you have the correct amount of K1 Micro in the Eazy

To clear the block you will need to drain down the outer chamber and clear the kiss points with a small flat screwdriver.

You will then need to refill the filter, the media should float up so it can remove by hand.

It is possible to retrofit a Nexus. However this cannot be done for an Eazypod.

  • You will need to check to see if your Airpump is working as it should be.
  • The airline holes may have become blocked with limescale. To rectify this you will need to drain down the outer section and check the airline for any blockages.