how the auto water changer works!

auto topup kit - pro4
auto topup kit - pro4
auto topup kit - pro4
auto topup kit - pro4
auto topup kit - pro4
auto topup kit - pro4
auto topup kit - pro4
auto topup kit - pro4

auto topup kit - pro4

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ATU-Pro4 fitted with an exterior sensor


This unit has been designed to be put straight into use with only a suitable container for reservoir being required.

SUMP MOUNT FOR THIS SENSOR AVAILABLE SOON! - this will be available at a reduced price to purchasers of the the standard version

includes everything needed to plug and play except reservoir container

overseas shipping available

via first class royal mail £3.50 (UK)

The version 4 has all the same features of the ver.3 - the difference is in the sensor type, its outside the aquarium not in!

IMPORTANT: it works by sensing the water level through the aquarium wall, it doesn't need to be tranparent and operates via capacitive sensing - this does have a couple of requirements, the glass or acrylic can be no more than 10mm thick and the sensor surface must make good contact with the tank

the mount supplied has been custom designed for us and secures by a single bolt (see pic) any decorative framework on the aquarium will need to be removed where the mount is located or the sensor cannot contact on the tank

providing your aquarium meets the above requirements your ATU4 will be accurate and reliable

The ATU-PRO4 is pre-wired and the unit is ready to use - includes:

  • The programmable controller
  • Supplied with sensor and mount
  • electronic variable pump
  • A 2amp power supply
  • 2 metres small bore pipe w/hook outlet
  • full installation guide online


In a nutshell it shuts down the pump so the top-up is inoperative until you come along and reset it, indication that it has shut down is via the pump LED starts flashing and the alarm sounds for 30 seconds, sounder then repeats for 2 seconds at 15 minute intervals. Reset is a simple push of the button, once to silence the alarm and twice to full reset - if the cause of the fault is still present then it will go back into alarm state

 BONUS - Anti-Wave - many are familiar with the pump switching on and off every time you stick your hands in the water, or the same things happens if you have that powerful wave maker powerhead. This is addressed by a 3 second built in float delay activation, in other words the water level has to be "LOW" for 3 seconds before the pump starts, as soon as the level reaches a "HIGH" position the pump stops. The distance between high and low level is not measurable by conventional means the sensor is that accurate!

BONUS - Memory - that preset time you set up stays unless you reprogam, it is not lost on power failure!


  • sensor - capacitive
  • sensor cable length 10"
  • water level variance - less than 0.5mm
  • voltage - 12v DC
  • alarm - visual and audible programmable 5-60 seconds, pump auto cut-off on alarm
  • pump - 12v DC with up to 3m head height and electronically adjustable
  • anti-wave - 3 second delay on pump activation
  • sensor mount - custom (exclusive)