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FREE SHIPPING on ALL ORDERS with NO MINIMUM Purchase. FUTURE DISCOUNTS on All Orders for All Customers, you don't need to be part of some group buy or exclusive program to enjoy reward points. Future discounts awarded in the form of points that can be used on future purchases. Excludes Ecotech Marine Products. FREE RETURNS on any order for 30 Days after purchase, we even pay the return shipping. Our Payment system is plugged directly into Apple Pay & PayPal Credit services so we never even see your credit card number when you order. We keep no credit cards on file.

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Automatic Top-Off Kit (ATK) - Neptune Systems

Neptune Systems

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Product Description

The ATK (Automatic Top-off Kit) is a simple, standalone, and complete solution for replacing water lost to evaporation.

  •     Plug and play ready. No mounts to assemble. No bare wires to attach.
  •     3 Levels of Safety Protection!
  •     Two optical water-level sensors (one for water level and one for emergency back up)
  •     IQ-Fill water run-time intelligence – learns how much water you use at each top-off
  •     Mechanical float valve prevents water overrun if electronics should ever fail
  •     Does NOT rely on ANY fault-prone mechanical float switches, temperature sensors, or capacitive sensors!
  •     Works Standalone (NO APEX NECESSARY!)
  •     Advanced features are unlocked when connected to an Apex (i.e. remote failure notification via text, email, or iOS alert)
  •     Includes PMUP, a powerful 24VDC pump that can push water vertically up to 14’
  •     Audible failure alarm
  •     Additional features with optional accessories

The new aquarium hobbyist has many challenges, but none is more annoying than the chore of adding water, every day, to make up for that lost to evaporation (a.k.a. topping off/up).  This alone usually makes the automatic top-off (ATO) device the first piece of automation equipment purchased.

The ironic flip side of this decision is that a faulty ATO device is one of the leading reasons for catastrophic aquarium failure, or even worse, flooding of the house or business.

Not all ATO devices are created equal. Sadly, many ATO on the market are made with cheap components, have very little protection against these catastrophes, and are just a nightmare to assemble and install correctly.

Three Levels of Security
1. Backup Optical Sensor - Should the main water level sensor fail, this second optical sensor is the backup. If water continues past the primary sensor, and then covers this one, the pump will be shut off and an alarm will sound.
2. IQ-Fill – Water run-time intelligence - If both the primary water sensor AND the backup optical sensor fail, the algorithm used in the ATK will not add more than double the learned water amount. It will shut itself off and sound an alarm.
3. Physical float valve – the final backstop

If for some reason all the electronic fail safes do not work, and water is continuing to be sent to the aquarium, the mechanical float valve is the safety device that will stop the water and prevent death to your aquarium and water on your floor.

An ATO does not have to be both a blessing and a curse!

We designed our ATK – Automatic Top-Off Kit to not only be super-simple to install and use, but it is unique in the market as an ATO device with three layers of redundant monitoring and water-level control. The ATK does the work for you, while at the same time protecting your tank and your home.

The ATK Includes:

  • FMM – Fluid Monitoring Module (runs standalone)
  • Pre-assembled water level mechanism with:
    • Magnetic acrylic mount (works up to 1/4″ glass/acrylic)
    • Two (2) optical water level sensors
    • Float valve
    • 90 degree tubing fitting
  • PMUP ATO Pump
  • 24V 36W power supply
  • 4m of orange RO tubing
  • 3/8″ -> 1/4″ push-fit adapter fitting
  • 1/4″ -> 1/4″ push-fit siphon break
  • Set-screw for non-float-valve applications

Product Videos

Neptune Systems - Reef-A-Palooza Orlando 2017 08:29

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Product Reviews

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  1. Another winner from Apex

    Posted by Daniel Melton on Jul 6th 2017

    This unit not only monitors my water level but has the capability to alarm if the water level is to high or if the water resivoir is low. (With additional eye sensor) It is a stand alone unit or can be tied on to your Apex units to send you alarms via email. It also has a capability to tie in a moisture sensors for leak detection. I used the ATK to replace the unit in my Red sea 450 which continually had issues. I set the unit up on about 10 minutes (because i needed to reverse the float and sensors)The quality is top of the line and would expect no less from Neptune. All on all this unit is more than what I expected. Would highly recommend it.

  2. Awesome ATO

    Posted by Jared on Jun 23rd 2017

    I upgrade to the ATK from a Tunze osmolator. As the other reviewer said, the little pump is powerful and very quiet. I first installed the ATK stand alone. Super simple setup - 5 minute process. A few days later I connected it to my Apex. Super easy process again. Just remember to update the ATK module, as you may have limited functionality in ApexFusion until it has been complete. Would recommend to anyone looking for an ATO.

  3. Great Product

    Posted by Chad on Jun 21st 2017

    Absolutely awesome product I have mine installed in basement feeds tank upstairs..Word of caution you will need to drill whole in floor larger than Orange feed tube because the 2 sensor also have to fit through hole...Second make SURE hole does not pinch Orange feed cable. Neptune and I went through dozens of emails trying to figure out why I had intermittent alarms and feed pump issues only to find I drilled hole to small and was pinching Orange feed tube. Customer support is amazing replyed on weekends.....

  4. Simple, Easy Install & Quiet

    Posted by Mical on Jun 17th 2017

    After seeing seeing demos and online videos I purchased this unit. Literally took 5 mins to install. Tested functions in "stand alone mode and it works flawlessly. Added bonus - it's quieter than any ATO unit I've ever had. If it got any easier, it would've installed itself.

  5. Perfect

    Posted by Nat on Jun 9th 2017

    I've avoided types of products, but the fit/finish on this top is amazing. Literally took minutes to install and gave up and running. Perfect in its simplicity, i can't imagine it being any better. And I don't have an APEX yet, but if their system is as good as the ATK, I'll be buying one soon.

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FREE SHIPPING on ALL ORDERS with NO MINIMUM Purchase for ALL CUSTOMERS! Future Discounts on All Orders for All Customers, you don't need to be part of some group buy or exclusive program to enjoy reward discounts. Future discounts awarded in the form of points that can be used on future purchases. FREE RETURNS on any order for 30 Days after purchase, we even pay the return shipping. No Restocking Fees. Secure Online Shopping Our entire site is HTTPS Secure and our Payment system is plugged directly into PayPal Credit services & Apple Pay so we never even see your credit card number when you order.

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Yes, we have CHANGED THE INDUSTRY. We are offering FREE SHIPPING on ALL ORDERS with NO MINIMUMS. Yes that's right. We are not happy with the current status quo. NO MINIMUM ORDER - FREE SHIPPING.

To reduce our shipping costs, all aquarium supplies are shipped UPS, Fedex or USPS. Orders can ship from multiple warehouses throughout the US. We attempt to keep inventory local to you to keep shipping times and expenses low. Our primary warehouses are in PA, TN and AZ. Most orders submitted by 3pm EST (Monday - Friday) are shipped same day. Orders on Friday and over the weekend after 3pm EST will ship Monday unless it's an item that ships out of a 24/7 warehouse. UPS orders will be delivered Monday through Friday. USPS or FedEx will be delivered Monday through Saturday. We deliver pretty much anywhere in the domestic 48 within 3 days FOR FREE!

Returns & Replacements

Personally we strive to never have any. But in the event, we like to make it easy. All returns are accepted within 30 days for any reason. Returns must be requested and pre-approved over e-mail to the From there we will email you a prepaid return label. Simply return your item within 30 days for a full refund.

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