how the auto water changer works!

auto topup kit - pro3
auto topup kit - pro3
auto topup kit - pro3

auto topup kit - pro3

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ATU-Pro3 fitted with an infrared sensor

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

includes pump/pipe/mounting etc 

overseas shipping available

via first class royal mail signed for £4.68 (UK)


Here are a few scenario's that have been reported on reef sites and what the ATU-PRO3 does if it happens.

  • The float physically jams because of a snail or similar
  • The float fails electrically
  • The float drops into the tank
  • The outlet comes adrift resulting in water outside the tank
  • The reservoir runs dry (possible pump burn out}
  • The pump gets jammed
  • and most important R.O. reservoir "dumps" its contents into the aquarium

In every situation above only the ATU-Pro3 or Pro4 will shut the pump down after a time period set by yourself with the options of 5, 10, 20 or 60 seconds. - exclusive to Reefloat - NO other brand has this facility

The ATU-PRO3 is pre-wired and the unit is ready to use - includes:

  • The programmable controller
  • Supplied with infrared sensor and bracket with 2m flex
  • A low voltage pump with a maximum height of 3 metres
  • A 2amp power supply
  • 2 metres pipe
  • full installation guide



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 immediately. 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 - HQ infrared
  • sensor cable length 2 metres
  • sensor mount magnetic
  • pipe - 5mm int 8mm ext
  • 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 2m head height
  • anti-wave - 3 second delay on pump activation

Customer Reviews

Based on 7 reviews Write a review

Customer Reviews

Based on 10 reviews
gary ross (Glasgow, GB)
Another ReefFloat Purchase.

I’ve bought multiple products from Gordon. Different tanks so different requirements. So a few ATUs and AWC units. All still in service. Just superior to anything else I’ve ever tried and I’ve tried them all. Service too is just unbeatable.


auto topup kit - pro3

Jim (Clacton-on-Sea, GB)
Auto top up pro 3

My original reefloat ATU system stopped working properly after I spilt water on the controller. 😫. Bought the kit with the infrared x1 sensor and replaced the whole system even though my pump was still working. Now have a spare pump. So simple to do: took about 5 minutes and operational immediately.
Service from Gordon was brilliant.

Martin Cowling
Don’t hesitate to get this ATO, you won’t regret it.

Being new to saltwater aquariums I got my reefer 170 a few months ago and soon realised how unreliable the stock ATO was, it was driving me nuts. Looked online and kept seeing the Reefloat Pro highly praised in the forums. Gordon was very responsive helping me choose the option for me. Easy to install and worked straight away, reliable and keeps my levels spot on. The support from Gordon has been brilliant, somehow I’d managed to mess a setting and Gordon emailed me a fix within an hour on a Sunday evening!

Alice cockerill
Best customer service

I went with Reefloat because of the impressive customer service record, which was not wrong. I cant imagine there is a better product out there for the job but what you are also buying here is the best customer service in any industry I've come across. Worth every penny! should I have any reason for future purchases I will stick with reefloat