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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 23 reviews
    Steven Webb (Halifax, GB)
    Auto top up kit pro4

    So far this is great piece of kit. No sensor in the tank to get dirty or salt encrusted.
    I found it difficult to place the control box as I use it on an AIO nano and the cable from the sensor to the control box is very short.
    It would be handy to have a line or mark on the sensor to show where it senses the water level but other than that it's perfect, very pleased.

    Christopher (Oxford, GB)
    Great ATU

    I've had bad luck with other ATUs and wanted to try something else this time around. So far the pro 4 ATU has been working very well for me on my nano AIO. As the sensor is on the outside it's easily adjustable and takes up very little of the precious available space in the rear chambers.

    Gavin Mcglashan (Cupar, GB)
    Reefloat ATO Pro4

    Why, oh why didn’t I buy one of these years ago. Such a simple but fail safe set up that just works perfectly with my 28g Nano with rear chamber. Can’t even hear the pump when it kicks in and it keeps my tank to the desired level, whilst keeping all tank perameters within safe limits. Absolute love it and it only took 5 minutes to set up.

    Newbie reefer (Croydon, GB)
    Amazingly simply but quality product

    I bought a pro4 auto top up kit from your website a few weeks back after looking around for several months. I simply couldnt understand why similarily popular auto top up kits were so expensive. Delivery was prompt and my package was suitably protected with sufficient packaging.

    I contacted Gordon with a question and I believe he replied within 2hrs. I had read several reviews on the excellent after sales customer care but I didnt expect such a quick response.

    I have now been using the pro4 top kit for about 2 weeks after manually stopping up RO water every day for 4 months. All I can say is it simply works. Instructions were very clear. Website says its plug and play and it is. The pump is tiny but totally silent and suitable for the purpose. I am surprised how similar set ups are nearly £100 more expensive than this. My local fish shop (ADC in Balham) recommended reefloat to me.

    Very pleased with my decision. I will recommended reefloat to anyone who is currently thinking of getting one.

    I am a newbie in keeping a mixed marine tank. In a hobby where everything is fairly expensive, it's nice to know that there are companies like reefloat that make quality products that dont break the bank.

    Paul Colquitt (Wigan, GB)

    Excellent customer service from Gordon highly recommend. Great product.