ATK Auto Top Off Kit - Neptune Systems

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  • Installing the Neptune ATK Top Off System - BRStv How-To

ATK Auto Top Off Kit - Neptune Systems

60% Recommend this to a friend (9 of 15)

SKU: 210837
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Quick Overview

The safest standalone ATO on the market!

The Neptune ATK System comes with everything you will need to get an automatic top off system up and running within minutes. The ATK can be used on its own without the necessity of an Apex Controller, but if you have an Apex, the ATK will integrate seamlessly into your system and give you bonus features.

  • Dual Optical Sensors

  • Float Valve

  • Includes PMUP and Tubing

  • Strong Magnetic Bracket

  • Multiple Levels of Safety

  • Compatible with any Apex


Ask a question

Product Questions

My rodi connects right to my sump under my tank. Is the pump removable on this unit and can i control shut off time without it?

Question by: Brian on May 25, 2017 5:48:00 PM
For an RODI supplied top off, you could replace the PMUP with the Neptune Solenoid valve, which can then control the flow of RODI water.

Happy reefing!
Answer by: Zack (Admin) on Jun 5, 2017 10:23:00 AM
Will the siphon break that is included in the atk be sold as a stand alone product?
Question by: Mike on May 28, 2017 4:24:00 AM
We're not currently aware of any plans to sell this part separately, but that may change in the future. The fitting included is basically a streight ro union with a small hole drilled at a downward angle. We do carry this type of union, which you could drill in the same fashion if you wanted to make the same sort of thing.

Have a great day!
Answer by: Zack (Admin) on Jun 5, 2017 3:50:00 PM
I have the new Apex, is there a way to use the ATK without using another power adapter? Can I use the PMUP connected to my energy bar and how does that effect the ATO built in program?
Question by: Dana on May 28, 2017 6:04:00 AM
If you have an open 1Link accessory port on your energy bar 832, the PMUP can be plugged into and controlled through this port without the need for a separate power supply. This will require that you locate the PMUP port and change the programming to follow the sensor inputs from the FMM, but this would be a very easy change to make in Fusion.

Have a great day!
Answer by: Zack (Admin) on Jun 5, 2017 4:09:00 PM
I'm going to run my ATO from my RODI reservoir. My reservoir is located in my garage. Only a wall seperates it from my aquarium so it is only 4 feet away once I run the RODI line through the wall. Obviously my reservoir will be higher than my sump. It will be 5 feet from ground level. Would I be able to use the ATK ATO for this type of set up? If not what do u recommend for this particular set up?
Question by: Jesse on Jun 9, 2017 12:20:00 PM
There is an inherent risk with setups where the reservoir is higher than the delivery area, since this can lead to a gravity siphon. The ATK does incorporate a fitting for the reservoir to create a siphon break to prevent this, but these types of measures *can* fail. Aside from the siphon break, the ATK does also use a float valve on the delivery module, so this provide another measure of safety from overfilling.

Happy reefing!
Answer by: Zack (Admin) on Jun 13, 2017 11:22:00 PM
Can nuptune ato be used with kale reactor
Question by: Kenneth on May 29, 2017 12:30:00 PM
It may depend partly on what type of kalk reactor you have, but the Neptune PMUP/ATK system should be compatible with any reactor that is set up to accept feed water from a small ATO pump and then deliver this water to the sump.

Have a great day!
Answer by: Zack (Admin) on Jun 6, 2017 4:56:00 PM
How long is the controller cable for the pump? Want to run it out to my RO container in adjacent garage, about 25 ft. away.
Question by: Robert Harter on May 30, 2017 2:02:00 PM
The PMUP has a 6ft cable with a plug for the 1Link accessory ports located on the 1Link, FMM module and EB832 energy bar ports. The optical sensors are 10ft long, which allows for a total spread of about 14-16 feet. As an independent ATO (without the Apex), this system is not designed for remote applications. If you do have an Apex, you could use a 1Link module located near the reservoir, connected via an aquabus extension cable, and you could then plug the PMUP into this module instead of the FMM by the tank.

Have a great day!
Answer by: Zack (Admin) on Jun 7, 2017 2:59:00 PM
Can I hook their solenoid up directly to my R.O.D.I. and forego the pump and resivoir.
Question by: Keith on May 31, 2017 7:42:00 AM
The Neptune solenoid can be placed on your RODI line and could then be plugged into the system in place of the PMUP to control incoming water.

Happy reefing!
Answer by: Zack (Admin) on Jun 7, 2017 3:56:00 PM
Can this work with the Apex Jr?
Question by: Eric on May 23, 2017 11:36:00 PM
The new ATK is able to be used independently or can also be connected to any of the current production models of Apex, including the Jr!

Happy reefing!
Answer by: Zack (Admin) on May 30, 2017 3:16:00 PM
How long are the leads from optical sensor to the fmm?
Question by: Mike on May 24, 2017 12:11:00 AM
The OS-1 sensor has a cable length of just under 10 feet. If we can be of further assistance, please let us know!

Happy reefing!
Answer by: Zack (Admin) on May 30, 2017 3:54:00 PM
Does the siphon break allow the water flow to be sent to the sump?
With my "German" ATO I have to direct flow to the display tank.
Otherwise once started by the pump, the reservoir would be completely drained by the siphon effect. Bad!
Question by: Bob on May 24, 2017 6:47:00 AM
The ATK does include a 1/4" x 1/4" inline push connect fitting with a siphon-break hole in it so that if your reservoir water level is above the sump water output point it will not generate a gravity-fed siphon. This should be used with caution and maintained frequently to prevent possible failure due to clogging if used with kalkwasser or other additives in your ATO water.

Happy reefing!
Answer by: Zack (Admin) on May 30, 2017 4:28:00 PM
Is there a safety feature to shut off the PMUP in case ATO reservoir is empty?
Question by: Jason on May 24, 2017 8:27:00 AM
The ATK has a couple of options to protect the pump from running dry and/or overfilling your tank. The ATK has a built-in "IQ Fill" feature that will keep a running average of how long it takes to top off evaporation in your system, and will never pump more than double this average. In addition, if you purchase an extra OS-1-M probe, you can plug this into the 3rd probe port on the FMM module and put the sensor near the bottom of your reservoir, and this will then detect if the water reaches the bottom and will turn off the pump.

Have a great day!
Answer by: Zack (Admin) on May 30, 2017 4:34:00 PM
What's the maximum distance for the pump? I'd like to have a top off reservoir in another room. What are the stats on the pump? Is it just the utility pump? Can I use another pump with this system?
Question by: Michael Roggio on May 24, 2017 8:59:00 AM
The PMUP utility pump is supplied with the ATK for moving top off water, however if you wish to use a different pump you can plug any pump of your choice into one of the Energy Bar outlets and can then tell this outlet to turn on or off based on the sensor inputs from the FMM sensor probes. The sensors have 10 foot cables, and the PMUP has a 6 foot cable and much be plugged into the FMM module or a connected 1Link port that is attached to the Apex system by an aquabus cable.

Hope this helps!
Answer by: Zack (Admin) on May 30, 2017 4:40:00 PM
Is the magnetic holder and sensor unit sold separately for people who already have an Apex FMM?
Question by: Patrick on May 24, 2017 10:27:00 AM
The magnetic mount is not currently available separately from the ATK, though this may change in the future. Neptune does have the OS-1-M probe/magnet assembly which can be purchased separately if you are looking to add optical sensors to your FMM.

Have a great day!
Answer by: Zack (Admin) on May 30, 2017 4:44:00 PM
Is there going to be an option to purchase the kit without the FMM? I already have the FMM, so I don't need a second one.
Question by: Tim on May 24, 2017 1:04:00 PM
I'm not aware of any immediate plans to make the magnetic mount/float valve assembly available separately, but I wouldn't be surprised to see this available in the future. Neptune does currently offer the optical sensors with a magnetic mount if you wanted to purchase these and a PMUP and create your own ATK-type setup.

Happy reefing!
Answer by: Zack (Admin) on May 30, 2017 4:50:00 PM
My sump is lower than my ATO reservoir. Does this kit have a solenoid for my situation?
Question by: Flagg37 on May 24, 2017 1:10:00 PM
The ATK does include a push-connect siphon-break fitting for situations where the reservoir water level may be higher than the output of the pump. They do also sell a normally closed solenoid which can be connected via a 1Link accessory port if you wish to have a mechanical control on the water flow.

Happy reefing!
Answer by: Zack (Admin) on May 30, 2017 4:53:00 PM
If you have your top off tank in another room are you able to program the pmup to operate from an EB4 or 8 or does it have to be plugged into the FMM
Question by: Anthony C on May 24, 2017 3:37:00 PM
The PMUP does have to be plugged into one of the 1Link Accessory ports. If you have one of the new EB832 power bars, these do have ports for this, or you can use a 1Link or FMM module, but the PMUP can not be plugged into a standard outlet.

Happy reefing!
Answer by: Zack (Admin) on May 31, 2017 9:45:00 AM
I have a 20 gal Fusion Nuvo nano tank. Will this ato work without the float. No room for that in the back of my tank

Thank you
Question by: Doug Bernhardt on May 24, 2017 3:59:00 PM
The float valve can be removed for setups where there isn't room. This does remove a layer of redundancy/saftey, but this is still a system with multiple failsafes to protect your tank from overfilling.

Happy reefing!
Answer by: Zack (Admin) on May 31, 2017 9:47:00 AM
What is needed to mount the pump in the basement approximately 30-40 feet away?

The head pressure will be less than 10 feet

Question by: Jason on May 25, 2017 9:14:00 AM
For extremely remote applications like this, you may find that the system is not capable of that configuration, or at least not without possible modification. The pump may be able to push the water this far, but it only has a 6 foot cable which has to be plugged into a 1Link/Accessory port on the FMM or Apex system. Due to the need of the optical sensors to be plugged into the FMM as well, this may be a limiting factor in the distance you can locate the reservoir from the tank. If you have an Apex system, you could alternatively get an extra 1Link module and locate this by the reservoir and plug the PMUP into it, and then you would just need an Aquabus cable to span the distance and connect the 1Link module to your Apex system.

Hope this helps!
Answer by: Zack (Admin) on Jun 5, 2017 9:59:00 AM

Full Details

ATK Getting Started


The Neptune ATK can be used on its own, or in conjunction with any Apex Controller. Neptune's Auto Top Off Kit comes with everything you will need to have a functional and safe ATO system. The FMM module is the brain of the operation and has an indicating LED light along with an audible tone letting you know when anything goes wrong. 


Dual Optical Sensors

Optical sensors are used by most of the top rated ATO systems, and the ATK uses two optical level sensors that control the overall function of the system. The sensors are pre-mounted into the magnetic bracket, with the lower optic being the primary water level sensor, and the higher optic acting as a backup sensor that will turn the ATK system off if necessary.


Adjustable Float Valve

Each ATK comes with a 100% reef safe adjustable float valve that acts as the last line of defense against overfilling. Float valves are very reliable and if water ever rises to activate the valve, the flow of water will be physically shut off saving you from a possible flood. 


Smart Algorithms

Don't think Neptune just stopped at sensors, and float valves to keep your floors dry and your tanks water level perfect. They included an algorithm that will monitor and learn how long it takes to fill your tank on average. After that is determined the system will never run for more than twice the time required to fill the tank. For example, if your tank typically takes 10 seconds to fill, the ATK will never run for more than 20 seconds, and if your system takes a minute to fill, it will never run for longer than 2 minutes. 


PMUP Utility Pump

Each ATK includes the powerful PMUP that connects directly to the FMM module without the need for an additional power supply. The submersible PMUP fits is a variety of top off reservoirs and uses standard 1/4" OD Tubing (RO Tubing).


Got 90 Seconds? Watch how easy it is to set up!




Module Dimensions - 4.75" L x 2.75" W x 1.375" H

Mounting Bracket Dimensions - 6.5" L x 3" x 3.5" (loaded with sensors and float valve)

Pump Dimensions - 2.25" OD x 5.5" H

Max Tank Thickness - 1/2" (glass or acrylic)

Max Flow - 100GPH

Max Head Height - 14'

Tubing OD - 1/4"

Power Consumption - 17W


What's Included?

1x FMM Module

1x Power Supply

1x PMUP Pump

1x Pump to Tubing Adapter

1x Siphon Break Fitting

1x Magnetic Mounting Bracket

1x Adjustable Float Valve

2x Optical Sensing Eyes

1x 3' Aquabus Connection

13' Top Off Tubing



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  • Perfect By RBG on 8/9/2017

    Easy instal, redundant safety features. Worked well right away and still does,
  • Mixed feelings on this piece of equipment By Randall on 8/8/2017

    First, the good:

    You can tweak the Apex programming to give you very granular auto topoff control. For my 100 circulating gallon system, a Defer time of 002:00 and a Min Time of 030:00 results in 10-20 seconds of auto topoff every 30-60 minutes, which keeps the salinity very stable.

    The system comes with a siphon break valve, designed for systems with elevated RODI containers like the Red Sea Reefers. It works fine with pure RODI water (if a bit noisy), but I have no doubt it would clog quickly with kalkwasser-infused topoff water, as others have experienced; Neptune really should mention somewhere that this is not recommended.

    The bad:

    The default Apex programming is pretty bad, at least by my standards. You may need to tweak it considerably to provide small incremental topoffs rather than large disruptive ones on your system.

    If you don't have an Apex controller, best not to buy this system. The standalone features and limited configuration options are not attractive.

    The 'high level' optical sensor is pretty close to the low level sensor. If you use the high level sensor for an alarm, be prepared for endless false alarms if you sometimes slightly overfill your sump, for example in preparation for acclimating new arrivals.

    The really bad:

    After 8 weeks, my low level optical sensor failed in the CLOSED state, and started leaking rust or something even more toxic. The contamination was bad enough, but the closed state meant that the ATK was going to think that everything was just fine as the water level went down down down and the return pump eventually stopped. Good thing I monitor my system obsessively. And that I had a spare optical sensor. From other people's experiences with this device as well as with the DOS DDR containers, it seems like these optical sensors are not really up to long term use in harsh chemical environments.
  • Best Ato By Inks on 8/1/2017

    I've used tunze but I like this one better
  • Defective out the box. By Golden Pond on 7/28/2017

    I usually don't post negative reviews but this one really got to me. Where you plug the pump into the control box the pins are to small for the harness and after days of my water staying low. I finally figured out the problem. Had to zip tie the wire to the power cable to put enough side force to make the pump run. Box feels really cheap. $200 bucks for this. Buy the Tunze!
  • Nice product By Scott on 7/25/2017

    Essentially a great product with multiple safety redundancies vs my previous Tunze. Well made and functions well. The alarm is very faint and must be powered down to reactivate. Love the anti-siphon function in the reservoir. I am not sure why the float valve is so gigantic. It is the largest part of the whole in sump apparatus plus taking up a lot of real estate. These are just minor things as I compare to my previous very small Tunze.
  • Bad optical sensor By Gene on 6/22/2017

    As always another defective item. The optical sensor always reads closed. So as usual with apex support they try to make it hard for you to get a replacement.
  • BE WARNED By Dani Zani on 6/18/2017

    I ran this in offline mode on my frag tank. Never again. Alarm tripped and ATO stopped over the weekend. In 40g frag tank this was a big deal!! Could have burned up my pump!!

    Alarms should reset!!!

    To fix I'm removing second sensor from water, and putting aside. But man, never had this problem with any other systems.
  • Easy to Install and QUIET By Mical on 6/17/2017

    I've had a handful of different ATOs but this one by far is the easiest to install. Literally took minutes. Added bonus it's super quiet. Tested all functions in "stand alone mode" and it worked flawlessly. I like the redundancy and triggering of faults - yes you have to reset power but that's a minor nuance. The plus' outweigh the inconvenience by far.
  • Don't think an ATO could be made any easier By Jonny on 6/15/2017

    I have needed an ATO for a while - been procrastinating cuz there were just SO many choices. Saw the BRS video on this one so I thought Id give it a go. All I can say is that I wish all aquarium products were all this easy to set up. Litterally had it working in about five minites. I don't have an Apex - didn't think I needed one - but this ATK product has me looking closer now
  • Excellent in Both Modes By Eric on 6/9/2017

    I've used the ATK in both standalone and apex connected and both have worked great. I first tried it in standalone mode for a very small tank (12 gallons) and was impressed with its ability to keep a very small amount of water stable without overfilling or causing false alarms.

    There are lots of built in safety features that make this a robust top off system. Different sensors and a manual cut off float valve prevents overfill and due to built in programming its made to stop if it runs too long. The ATK will not turn on unless the low sensor is actually low for a full 10 seconds. This eliminates random fluctuations. It will also turn on the pump for at least 4-5 seconds. This prevents super short cycles on the pump that may trigger if the water level is barely bouncing at the bottom sensor. The main gripe is that you do have to power cycle the FMM if an alarm occurs. Luckily the one thats most likely to trigger is the top optical being under water. There however is a 10 minute delay before an alarm will sound. This means something most likely did go wrong and it wasn't just a feed mode or return pump restart issue.

    In Apex connected mode you do lose the audible alarms and IQFill but you gain the power of controlling all of the code and timed events I listed before. I really lengthened the bottom optical sensor delay before it starts its top off. This means it won't trigger while siphons and filters are restarting. During this time there may be a drop in the return chamber of a sump, and I don't want it to trigger as its a false low. You can also put in Feed mode delays and power off delays for the same reason. The biggest of all is probably text/email alerts. Having an audible alarm is great, but its not that helpful if you are at work or outside at the time that something goes wrong. Being able to immediately get notified and then take appropriate action inside Apex Fusion is amazing.
  • Design flaws By Chris on 6/8/2017

    There are several design flaws with this kit especially if you use kalkwasser in your top off like most reefers do.

    1.The siphon prevention is a tiny pinhole in a tubing adapter. Pretty much gets clogged right away unless you have nothing but pure RODI water and no additives you are doing through topoff. I used my own T junction with a larger hole to fix it.

    2. The float shutoff is a really cheap part with another pinhole output that gets clogged after a few days. I took it apart and made the hole larger with a drill and it clogs no more and still shuts off.

    3. The pump is really a cheap product after 1 week it quit with a loud buzzing noise. I took it apart and one of the impeller fins has broken off and and stopped the motor. I cleared the broken fin and I am running it with one less fin.

    4. The outlet for the Apex dashboard physically shuts off the outlet for some reason instead of just switching it to the off state. You have to manually correct it from the dashboard each time it shuts itself off in the event of an error. This may be ok for some folks who want ultra safe shutdown in case of emergency. I fixed this by extended the pump on time in the interface to 4 minutes but also #2 above fixes the problem as well but has the drawback of adding too much water too fast.

    5. I contacted Neptune Systems support and they merely offered to replace the pump after I jumped through a series of RMA procedures. What I would really like to get is a better quality build in the manifold.

    Overall, the best part about this product is the Apex Fusion integration where I can see what is actually going on. I replaced my Tunze Osmolator with this product and I was going to take it out after a week of using the product but it has saved my bacon over the week I have owned this product as a backup when this one is not working properly and I needed to fix the parts.

    As a note: this product would work a lot better if you do not use kalkwasser in your topoff. If you do use kalkwasser, make the mods I mentioned and then hang the pump a lot higher in the tank so that it can't possible suck up anything other than saturated solution. If you want the Apex integration and you can make the mods above, then buy this thing, otherwise, just look at the Tunze osmolator or another product that is better crafted.
  • Best ATO on the Market By Greg on 6/8/2017

    This is probably the single best ATO now on the market. Works stand alone without an Apex. 4 options of measure water levels before disaster. Nothing out there can compete at this price. You should not hesitate to buy this product.