how the auto water changer works!

atu3-programmable - 50 litre
atu3-programmable - 50 litre
atu3-programmable - 50 litre
atu3-programmable - 50 litre

atu3-programmable - 50 litre

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Auto Top Up (not water changer)

ATU-Pro3 - 50 litre fitted with an infrared sensor 

D:500mm W:300mm H:370mm (height does not include the cap- add 50mm)

This unit has been designed to be plug and play

includes pump/pipe/mounting etc 

shipping £12.50 uk mainland


Here are a few scenario's that have been reported on reef sites and what the ATU-PRO 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-Pro 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-PRO is pre-wired and the unit is ready to use - includes:

  • The programmable controller
  • choice of infrared sensor and mount with 2m flex or capacitive sensor
  • A low voltage pump with a maximum height of 3 metres
  • A 2amp power supply
  • 2 metres pipe
  • 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!

Customer Reviews

Based on 2 reviews Write a review

Customer Reviews

Based on 6 reviews
Matt Carpenter (Coventry, GB)
Fantasic bit of kit

A well overdue review, good thing is its after 3 years of ownership and use!

Brilliant bit of kit, just sits in my sump cabinet permanently and water changes are just flicking a couple of switches and valves.
Had it 3 years and never missed a beat, taken all sorts of abuse as well.
Literally Cant beat the customer support either, any issues I've had, mostly user error, service and advice is amazing

Thanks Gordon!

Tony Johnson (Hull, GB)
Atu pro 3

After some initial problems gordon sorted it out no quibble no problem even on a Sunday I'm 100 % happy with the unit couldn't ask for more highly recommend anyone give reefloat a try

Tashan (Edinburgh, GB)

Great customer service so far , and exception product i definitely feel that I've made the best decision to go with reef float product and already looking at investing on a AWC

Peter Mills (Gravesend, GB)

Very good product

Steve Cunningham
No more hassle

This unit takes auto top off to the next level. having an all in one set up that has been very well put together removes another task from the long list of maintenance tasks. A long sensor rod allows for really easy depth setting and a long robust braided hose allows for the unit to be a good distance away from your sump should there be a need. Great innovative product as with all the Reefloat range. When you buy one of these you will then find yourself looking at auto water changes too, Reefloat can fix that for you too.