Top [2023] 10 Best Auto Top Off System for Aquarium, Reef Tank

Top [2023] 10 Best Auto Top Off System for Aquarium, Reef Tank

Water is a very fundamental part of our life. How can we fill the tank without this, right?

However, the water also has a quality that can be uncomfortable for anglers. To lighten our burden, the Auto Top Off System was invented.

Comparison Table

CustomSiteStripe ImageTitleReviewBuy
Top PerformanceTunze USA 3152.000 Automatic Top Off Nano Osmolator4.2/5.0Check Price
cheapest XP Aqua Duetto Dual-Sensor Complete Aquarium Auto Top Off ATO4.5/5.0Check Price


Best Auto Top Off System can work for many types of aquariums. I am here to present to you a list of the Best Auto Top Off System for reef aquariums, saltwater aquariums, freshwater aquariums and many other types of aquariums.

Best Auto Top Off System is increasingly becoming a reality for the modern aquarist today. One of the most common applications of tank Auto Top Off System (AKA ATO). There are many, but what is the best Auto Top Off System? Today’s message tries to find out

These systems work to add fresh water to your aquarium while the water evaporates. In salt water tanks, they are extremely valuable for maintaining a stable salinity, as the salinity can vary as the water evaporates and is not replaced. In fresh water tanks, this ensures that the water level remains stable, so that your filtration can work optimally and your tank does not dry out completely.

Replacing evaporated water can be very tedious, especially for those with larger aquariums. Auto Top Off System make it easy for you to handle without having to lug around a bucket of water every day. However, you must be very diligent with the system you choose. Autofill systems can be fussy, and selecting poor quality can lead to a tank disaster and potentially an expensive home repair bill.

This is the reason for this post today. Autofill systems are great tools to make your life easier, but not all autofill systems are the same. I have used or have experience with most of these filling systems which I will be reviewing today. Before we get started, let’s discuss why a charging system is so good and what features to look for.


Top 10 Best Auto Top Off Systems for Your Aquariums

There are many options on the market and it can be confusing to choose a good one for your tank. So here’s a list of the 10 best autofill systems out there.


Best Auto Top Off System Reviews

1. Tunze 3155.000 Osmolator Auto Top Off System

Best Auto Top Off System

Tunze is a company that has been producing finishing systems since 1985. They are at the top of their game. The 3155 Tunze Osmolator is the world’s gold standard for Auto Top Off System.

The Osmolator is safe and reliable. It is a product that has been tested and built over many years and many previous models. The Osmolator is small at 4x1x2.5 inches in size and weighs less than 3 pounds. It is a single compact unit.

The Osmolator uses a set of two sensors to detect the water level. The main sensor is a mini infrared optical sensor that can provide very precise control. The second sensor is a float sensor, which serves as a backup sensor to measure the water level.

The Osmolator is easy to set up. The unit comes with magnetic brackets for easy and convenient installation. It comes with a complete hose, pump and feeding package. It not only recognizes the falling level of the water, but also effectively pumps water from the external source into the tank.

This product is one of the best on the market. Hence, it may be a bit more expensive compared to other products. The price is on the high side for an Auto Top Off System. However, you know you’re getting what you pay for, so the expensive label won’t disappoint you when it comes to product quality in this case.


  1. High-quality construction
  2. Small in size
  3. Easy installation
  4. Accurate estimate of the water level


  1. Expensive
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2. Tunze USA 3152.000 Automatic Top Off Nano Osmolator

Best Auto Top Off System

This is another product from the Tunze company. As mentioned earlier, Tunze has been manufacturing Auto Top off systems since 1985 and have built a reputation in the market. The Tunze 3152 system is one of their two best-selling Auto Top Off System.

This model is small at only 1.5 x 1.2 x 2.5 cm and weighs less than 2 pounds. It can be installed on a cabinet filter or right on the edge of the aquarium. The bracket / holder is magnetic, making installation easy and can be mounted on a glass wall up to 3/8 inch thickness.

The device comes with two sensors. The main one is a mini infrared optical sensor that can provide accurate water level control. There is also a backup sensor that floats in the water. Two-layer sensors make the system fail-safe and keep the quality of the entire system constant.

The device is very energy efficient. It only works with an 11V power supply and the pump is also on low voltage. It also runs fairly quietly so you don’t have to worry about system noise disturbing those around you.

This device is very small and handy and there is a trade off for that size. This Auto Top Off System can only work efficiently with a tank size up to 55 gallons. It can work in larger tanks, but the quality is not efficient enough for the whole tank and malfunctions can occur.

If your tank is less than 55 liters, this device is still a very good option as the price is much cheaper than its brother that can work in larger tanks.


  1. High-quality construction
  2. Small and favorable price
  3. Easy installation
  4. Quiet


  1. Only work efficiently in tanks up to 55 gallons
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3. XP Aqua Duetto Dual-Sensor Complete Aquarium Auto Top Off ATO

Best Auto Top Off System

Those who want something simple to use will like the XP Aqua Auto Top Off ATO. It has the smallest ATO sensor in the world. In addition, it provides you with two layers of overfill protection for the safety of your home.

Scheduling is smart, which means it detects when to turn it on and off. You really don’t have to do anything other than plug it in and let it work. In addition, the sensors work in the dark, so you don’t have to keep your lights on.

There is a secondary sensor that protects your home from flooding. The water level controls are very accurate. So you do not have to worry that you do not feel that there is already a lot of water.

Most people will enjoy not having to program or adjust the product before using it. Just configure and connect the sensors correctly. You will also receive all necessary installation parts, as well as a magnetic coupling.


  1. Two-layer overfill protection
  2. Very accurate water level controllers
  3. Plug and play installation


  1. Faulty sensors a possibility
  2. No Auto Top Off System shutdown for dry pumps
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4. IceCap Dual Optical ATO Auto Top Off Controller

Best Auto Top Off System

An Auto Top Off System (ATO) is one of the most important parts of your saltwater aquarium. That’s why you need to make sure you’ve picked the best one. The IceCap Dual Optical ATO Autofill Controller is ideal.

It is designed to monitor evaporated water and replenish it every day. This way you don’t have to manually add water to keep the water stable.

This ATO is a well thought-out system that is fully automated. It also includes a fail-safe design that uses two optical sensors. They regulate the water level of the receptacle and / or the aquarium.

Typically, the second sensor is there to provide real-time monitoring and protection in the event that the first sensor fails. There are no moving parts with this system, which prevents downtime.

If your fill tank is too low, the unit will warn you so that your sump / aquarium does not dry out. Moreover, it is easy to install. You don’t have to be a professional plumber or electrician to plug in and mount the sensors.


  1. Dual optical sensors
  2. Compact design
  3. Integrated failsafe
  4. Plug and play installation
  5. Including pump


  1. It can be caused by certain fish.
  2. Very bright LED; not ideal for bedrooms
  3. Twisted pipe out of the package; soak in warm water to soften
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5. Coral Box Auto Top Off Magnet Mount Pump Included N50

Best Auto Top Off System

If you want an affordable solution to maintain your aquarium water level, Coral Box Auto Top Off N50 is ideal.

It features a magnetic float switch, which is made of high-quality materials. This activates the pump when the water level falls.

The included pump is a great addition. The ATO will also switch off the pump when the float is at the ideal water level. You don’t need to program anything; just install the float where you want the water level in your tank.

This product is ideal for fresh and salt water tanks. Those who travel frequently will find that you can leave with an ATO without fear of flooding your space or causing the tank / sump to dry out.

In addition, you will find that the auto-fill function prevents your filter or skimmer from drawing in air due to a low water level.

As if that wasn’t enough, you can use this product with any size aquarium, making it ideal for all people and spaces. It also has a pump with a head height of up to 1.8 meters.


  1. Solid construction
  2. Extremely sensitive float (prevents flooding)
  3. Pump included


  1. Slightly weak magnetic holder
  2. Randomly activated float switches
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6. EPTTECH Aquarium Marine Reef Fish Tank Automatic Auto Top Off Water

Best Auto Top Off System

When you buy EPTTECH Auto Top Off Water, you get everything you need.

This includes the pump, ATO controller, power supply (plug), a hose holder and the hose itself. So you do not have to go out to buy a new pump.

As with some ATOs, the wiring is large or long enough to reach the aquarium. This can cause major problems over time. However, this product does not have that problem.

The magnetic installation makes it very easy to place in your aquarium or fish tank. In addition, you can place the sensors where you need them most. One thing to consider is that the place where the ATO will be installed must be clean and transparent.

You will find that this product has AFS (Auto Feedback Security) technology. It is a safety feature to ensure real-time protection against failure. Two alerts are available, including a red and a blue LED.

Blue light indicates that there has been a period of no-fill that is twice as long since the last fill. The red LEDs are there to indicate that there has been a flood somewhere in the system.


  1. Well built unit
  2. Small pump (included) works fine
  3. Ease
  4. Compact design


  1. Magnetic parts can break and expose the iron core
  2. Necessary redesign for the tube holder for an ideal fit
  3. Hard to understand instructions
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7. JBJ Auto Top Off – Budget Friendly ATO

Best Auto Top Off System

JBJ’s Auto Top Off System is one of the leading entry-level Auto Top Off System on the market. This system differs from the others on this list in that it has two manual float switches that are activated when the water level rises. There are no digital sensors in this Auto Top top of the system. In fact, I don’t mind dual floating sensors and with the two types of settings you can do with this ATO system, you can have a fairly complete testing and redundant system.

Another great feature is that this system is easy to adjust. You can change the sleep timer by extending the time on the controller and adjusting the shutdown with a screwdriver and you can also set an alarm when the ATO is on. That’s a really great feature for monitoring and preventing flooding if the float switches fail.

The controller will have an audible alarm if the maximum float switch is tripped and both float switches are reversible if required. It really offers a lot for its price.

What I don’t like about this system is that you have to buy a pump and the mounting options aren’t that great. There is a suction cup mount option, which I wouldn’t recommend, and the bracket mount options just don’t look very nice to look at and can get weird if you have a rimless tank or crankcase. The lack of a pump generally confuses me with Auto Top Off System. I tend to lean on systems that come with pumps as they take the guesswork out of having to do.


  1. Fair price
  2. Easily customizable and personalized
  3. Auto Top Off System shut-off function


  1. Suction cup mounts (use mounts instead!)
  2. Does not contain a pump
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8. Hydor Smart Level Controller – Dual Sensor ATO For A Reasonable Price

Best Auto Top Off System

The Hydor Smart Level Controller is an ATO system that uses a dual sensor to control the water level in your aquarium. The sensors are contained in a single plug, making them easy to install. It is a sump based ATO system so I would not recommend it for use in the tank as the alarm level is set very high when used in an aquarium. It has a double alarm system with light and sound. The sensors are not affected by the waves in the tank.

What I don’t like about this Auto Top Off System is that it doesn’t come with a pump. You have to buy it separately, so the price may not be as high as it sounds if you buy a more expensive pump. The switch holder is also a hybrid magnet / extractor. I prefer a real magnetic holder.


  1. Fair price
  2. Alarm
  3. Dual sensors


  1. Without manual switch
  2. Not a real magnetic switch bracket
  3. Exclusive pump!
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9. Autoaqua Smart Automatic Top Off System

Best Auto Top Off System

This is not just an Auto Top Off System. It’s a smart ATO. Includes the pump and hoses, which can pump at speeds of 74 gph to a delivery head of 2.5 feet. It also has a universal bracket.

In addition, it uses a unique non-contact digital sensor. It also has built-in Auto Feedback Security (AFS) technology for real-time failsafe protection.


  1. Since it comes with a pump, all you need is a bucket for the water in your aquarium.
  2. The sensor contains no moving parts and there is absolutely no risk of voltage leakage.
  3. Gives a warning if it is not filled or if the filling time is too long.
  4. It also comes with a 2-year warranty.


  1. You will run into the same problem with Autoaqua Smart: it is not that reliable. It may work for a while and then it may not.
  2. And then you might have some rust problems in about a year or 18 months.
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10. Aquarium Triple Sensor Auto Top Off Water Filler

Best Auto Top Off System

The Triple Sensor Auto Fill Aquarium Water Filler is an ideal solution for your aquarium. This smart water refill device meets the needs of those who don’t always want to refill their tanks due to evaporation.

Three sensors are included, so you never have to worry about mistakes. The optical level sensor monitors the water level and determines whether the water needs to be topped up. In addition, the S1 sensor prevents flooding, while the S3 sensor monitors water shortages throughout the system.

You will also find an alarm and various status indicators to prevent errors. For example, indications have been included for an overflow sensor and a missing pump. If an abnormal situation occurs, the buzzer will sound and the LED will light.

This product has an all-in-one system. The package includes a power adapter, controller, tube holder and charging pump. Plus, you also get a PVC tube, three sensors, and a magnetic base.

Although you will need to install the product, it is quite easy to do this. The instructions are clear and concise. You also do not need to adjust or program the product before using it.


  1. Alarm for any problem
  2. Magnetic sensors stay where they are
  3. Three sensors included


  1. Confusing instructions
  2. Design errors for the placement of the optical sensor and float valve
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What is an Auto Top Off System?

Water evaporates at any temperature. To maintain an aquarium or aquatic aquarium, this water feature can be problematic. Every day there will be less and less water in your aquarium.

And if the water gets too low, it can pose a serious problem for your fish and aquatic plants. To save anglers from this problem, the Auto Top Off System (ATO) was invented for the best convenience of all.

An Auto Top Off System is a system designed to Auto Top Off System detect the water level in your tank with a sensor. Whenever the sensor detects that the water level falls below a certain point, the system automatically replaces the evaporated water so that the water level in the tank can return to the optimum level.

Without this system, you may have to carry a bucket of water, pour into the tank, and clean up any spilled liquids. Having to do that almost every day can be a daunting task. But with an Auto Top Off System you don’t have to do all those things. Salinity is also stable with the system. The Auto Top Off System prevents the pump from drying out.

The Auto Top Off System is not only useful for your daily life to maintain your aquarium, but it is also especially useful when you are not at home. You can set up an Auto Top Off System fish feeder on the go, but it won’t do much for your fish if you return to a fully vaporized, waterless tank.

The Auto Top Off System ensures that the tank is filled with water and does not allow the tank to dry out and destroy the habitat of your fish and aquatic plants.


What is the Best Auto Top Off System?

When choosing the best auto fill system for you and your tank, keep the following in mind:

What’s in the package?

Typically, the base kit for an auto-fill system package would include a self-leveling controller, one or two sensors, and mounting hardware.

Sometimes the complete package also includes a pump and hoses. The pump is an accessory that you should pay attention to. If you already have a pump with you, you do not need the supplied pump.

But if you don’t already have one, choosing a complete package including one included can save you a lot of time setting up the system.

How does the installation process go?

Would you mind getting everything ready and complicated during the installation process?

If you are a crafty person then you don’t have to worry about which choice to choose this step because you can do it all. However, if you’re not the smartest person ever, opting for something easy to install and configure on your tank can save you a lot of energy and effort. Many systems come with magnetic supports. They are very easy and simple to install.

How big is your tank?

Usually the Auto Top Off System does not take the size of the tank into account. But bombs do.

So check the system pumps or the pumps you already have, see what their options are. If the pumps are too weak, it will take a long time to fill the tank.

What is your budget?

As when buying anything, you need to consider your budget. There are quite a few other accessories you should buy for your aquarium, so don’t let the auto fill system take up your entire budget. Pick one that you can easily afford.


How to Set Up an Auto Top off System?

1. Remove all your supplies from the box. Before installing anything, turn on all units and test the sensors and pump to see if they work. If there are noises or a light alarm, check if they are likely to work. It is much easier now to test the device than it is to have to take them out of the tank later because they are not working properly.

2. Just prepare an empty tank. Do not fill it with water yet. It is safer and easier to work with an empty tank during setup.

3. Have a reservoir of fresh water ready next to your aquarium. It can be a bucket or a large pitcher. The smaller the opening, the better with the reservoir, as the water is more difficult to evaporate and you need to replace the reservoir less often. I recommend using a jug with a small lid, similar to a gas bottle. Drill or cut a hole in the cap, large enough for the tube to pass through later. With the lid closed, the exposed water surface is limited and therefore the evaporation of the water from the tank is kept to a minimum.

4. There would be two sensors with the device. They must float in the water for the whole unit to function properly. Put one in the fresh water tank. The other should be installed in the crankcase just above the waterline. Sometimes some devices come with special or smart sensors that work differently from the other commonly used sensors. If so, read the supplied manual carefully to set them up correctly. The sensors are the most important part of the whole system.

5. Prepare to install the pump. There should be two outlets on the pump: the “inlet” and the “outlet”. Route the hose from the fresh water tank to the “inlet” of the pump. Then run another tube from the “outlet” of the pump to the crankcase. Try to keep the hose above the waterline when installing the outlet hose. If the tube is submerged it is possible to create a siphon on the back and accidentally suck all the water from the tank into the reservoir, which is the opposite of what we want to do with the system.

6. Connect the device to an electrical outlet. Make sure your hands are dry when you connect the device. Also make sure there is no water near the outlet. It can be dangerous so there is no harm in double checking.

7. Finally fill the reservoir with fresh water and your Auto Top Off System is ready for use.



An best Auto Top Off System is not an absolute accessory for your tank, but it is very handy and handy. With an Auto Top Off System, you almost never have to worry about your tank again during a long absence.

If you are looking for an ATO system, do your research and answer all the questions I mentioned earlier in “What is the Best Auto Fill System?” Section. You can also read people’s reviews and comments about products online to learn more about the product’s quality, strengths, and weaknesses.

When you buy one, make sure you’re happy with your choice. And a good quality functional ATO system will ease your mind and keep your fish and plants happy and healthy in your tank.