how the auto water changer works!

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

auto topup kit - pro3 programmable

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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 15 reviews

Fast and fantastic service.

DEREK RAYNER (Manchester, GB)
Best Atu I’ve ever had

I have had numerous Atu’s on my marine tank in the past 6 years all have given me problems.They have either not worked properly or worse still dumped half of the top up reservoir water into my tank seriously affecting my water stability.This Reefloat Atu is a completely different piece of equipment.I have multiple wavemakers and due to it’s anti wave technology no false alarms or accidental overfilling whatsoever.The ability to program the shut off period is another piece of mind factor.All the equipment feels really well made.Customer service is also very good if you have a query(which I had and was answered promptly)If you have a reef tank with corals and fish worth hundreds the extra cost of the reefloat auto top up kit pro 3 is well worth it.Very highly recommended.

Chris H (Wisbech, GB)
One of the more reliable ATO available

Very reliable units

J.C. (Preston, GB)

I bought a sensor from Gordon it arrived excellently wrapped. I had to speak to Gordon about setting it up. He was excellent, new what he was talking about and had it set up and working perfect within a few minutes. I found Gordon to be very helpful and I will give him all my future business if he can help. Thank you very much Gordon. Just to say sorry for troubling your self and your wife with ringing you. John Catterall

not a problem

Jason Stirk (Manchester, GB)
Brilliant product

Had a few issues with the branded ATU and found this through a forum and must say, not disappointed.