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auto topup kit - pro4

auto topup kit - pro4

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  • sensor cable length 40cm (designed to be positioned alongside the controller-we do not advise extending the cable length)

suitable up to 9mm glass/acrylic, clear or not clear

overseas shipping available

The ATU-PRO4 has all the same safety features of the ATU-PRO3 - the difference is in the sensor type, its outside the aquarium not in!

2 year sensor guarantee!

ATU4 is pre-wired and the unit is ready to use - includes:

  • The programmable controller
  • Supplied with sensor and mount
  • 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 40cm (designed to be positioned alongside the controller-we do not advise extending the cable length)
  • 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 
  • anti-wave - 3 second delay on pump activation
  • sensor mount - custom (exclusive)

    Customer Reviews

    Based on 3 reviews Write a review

    Customer Reviews

    Based on 17 reviews
    Steve Hemingway (Wakefield, GB)
    Reefloat atu

    Easy to install/setup and works like a dream😁

    Tony Marsh (Saint Neots, GB)
    Brill bit of kit

    This AT is really great, on top of that great service from Gordon. I ordered on a Friday and it was here by Saturday morning. Completely surpassed my expectations, easy to set up and nice and quiet. Bravo!

    tony bowles (Barry, GB)

    Has only been fitted for a few days but seems to be working fine

    Adrian Haynes (Oxford, GB)
    Auto top up

    This is the 3rd auto top up I’ve purchased over many years - I’ve never had any problems with all my purchases - to be honest they just get better and better - I would highly recommend this seller - as a marine hobbits - a- ATU system is one of the no 1 components needed to run a successful marine aquarium - don’t go with inadequate unreliable ATU - as I made the mistake some 12 years ago and cost me dearly - very happy customer 👍

    Toby (Sittingbourne, GB)
    Does as is described

    A wonderful little piece of kit. Took me a while to set it up, but once it was it's run perfectly