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Auto Top Off

Auto Top Off

106 reviews
$ 99.99

Finally, a top-off control sensor that is mounted to your sump with a magnet rather than a clunky bracket!  Driven by a pressure-sensitive switch located in the relay box, a strong magnetic field won't affect its operation.  The sensor tube can't get clogged with calcium deposits or activated by wayward snails as there are no moving parts.  Our top-off system is capable of maintaining the sump water level within +/- 1/4" tolerance (1/2" overall) and features a built-in range buffer or hysteresis effect, which prevents rapid on-off switching that sometimes occurs when cheap float switches bob up and down in small waves.  The magnet bracket is capable of holding on up to 1/2" thick glass.  The slim design relay box is unobtrusive and can handle up to a 3 amp pump at 110v AC.  The green LED light indicates when the circuit is active and the pump is running.

The magnetic bracket also contains both an adjustable 1/4" to 1/2" fitting, useful for holding the tube from your top-off pump in place.  This fitting can be switched out for an optional backup mechanical float valve, which will physically close and stop the flow from your pump in the event of an electrical or switch issue.  

Our digital output version is now available for use with most aquarium controllers.  This version is designed without an outlet; just plug the ATO pump into your controller's relay box and set up the controller to read the pressure switch state (see instruction manual for details).  It is available with the plug types of several popular aquarium controllers.  For example, Neptune Apex uses a "minidin-8" style plug.  To use this, simply plug into the port marked "I/O" on the controller, and program according to instructions.  If you already have something plugged in to that port, you will want to use their Breakout Box and select the "bare wire" option below.  See instruction manual for further details. Bare wire connection is 2 strand, non-polarized 22 AWG shielded wire.

The Digital Output version allows several non-standard uses for this switch. For example, it can be a low level sensor in your sump that is impervious to coralline algae and snails, can turn off your return pump and send you a text message at the same time. There are a lot of options since you can reverse the logic of the switch at the controller.

Our switch and all components are made in the USA. 

Technical Data:

Water level sensitivity: 1/2" 
Magnet strength: up to 1/2" glass
Magnet bracket dimensions: 1-3/4" front to back x 2-1/4" wide (excluding external magnet half, 1/2" thick)
Switch box dimensions: 4" x 2.25" 
Input power: AC 110v
Relay box capacity: 3 amps
Switch rating: 10+ million cycles
Warranty: 1 year

Click here for Standard outlet box ATO installation manual
Click here for Digital output ATO installation manual

Click here for ATO and related Pressure Switch troubleshooting guide

Customer Reviews
4.9 Based on 106 Reviews
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  • Avast
  • auto top
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  • Apex
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Great product and customer service

I always used optic sensors in the past and have found the pressure sensors by reviews and have to say I’m impressed so far. Customer service is top notch

Jeff W.
United States United States

Best ATO at any price

This is my second unit, although the first was wired to a Reefkeeper Elite controller as opposed to the current stand-alone model I just purchased for a new 195 gallon setup. I used the first one for about 6 years prior to taking down the previous 125 g tank for a move. During that time it was 100% reliable, and I like that there are no moving parts or optical sensors to break or get fouled. It's a shame this excellent product never gets included in any of the meta ATO reviews.

Alex O.
United States United States

Avast ATO

2nd one I have purchased so far. The sensor seems to be larger than what I remembered though.

robert q.
United States United States

Profilux digital output not working

Ordered the profilux digital output version of the auto top off. After extensively searching the net and the popular reef forums. I have concluded that this is not a plug and play device. I am unsure what it is I have to do but the profilux does not register the signal from the control box. Recommend others to just get the switch version. Have had it for years with no issue.

John P.
United States United States

Auto Top Off

Great customer service. The folks walked me through all parts that I needed to complete my purchase.