Auto Top-up

Aquarium Auto Top-up Systems compensate for any water evaporation in an aquarium and are essential for keeping a stable water level and water parameters in your aquarium. ATO units that work on float switches or sensors are available from Charterhouse Aquatics who stock all the biggest brands including TMC, AutoAqua, Tunze and Pacific Sun. 

Aquarium Auto Top-up Systems compensate for any water evaporation in an aquarium and are essential for keeping a stable water level and water parameters in your aquarium. ATO units that work on float switches or sensors are available from Charterhouse Aquatics who stock all the biggest brands including TMC, AutoAqua, Tunze and Pacific Sun. 

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 Have questions about Auto Top-up? Checkout out our FAQ!  Don't buy the WRONG Auto Top-Up unit! Watch This First!

Don't buy the WRONG Auto Top-Up unit! Watch This First!

Thinking about getting an auto top-up unit or looking to upgrade, well this video is for you. Not all units are created equal! In this video, we break down the key differences between the auto top-up units available, help you decide which one you should buy, and why they’re an essential bit of kit for your aquarium.

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Have Questions About Auto Top-up?
We Have Answers.

Get quick answers to common questions about Auto Top-up

1. What is an Aquarium Auto Top-Up (ATO) System?

An Aquarium Auto Top-Up (ATO) system automatically replenishes evaporated water in your aquarium. By maintaining a consistent water level, ATO systems help stabilize salinity and water chemistry, which is essential for the health of your aquatic life.

2. Why do I need an Auto Top-Up system for my aquarium?

Water evaporation is a normal process in any aquarium, but it can lead to fluctuations in water levels and salinity—especially in saltwater tanks. An Auto Top-Up system automates the refill process, ensuring a stable environment for your fish and corals, reducing maintenance, and protecting sensitive livestock.

3. How does an Aquarium Auto Top-Up system work?

An ATO system typically uses sensors (optical or float switches) to detect water levels in your aquarium or sump. When the water drops below a set point, the system automatically activates a pump to add fresh RO/DI water until the level is restored.

4. What types of Aquarium Auto Top-Up systems are available at Charterhouse Aquatics?

What types of Aquarium Auto Top-Up systems are available at Charterhouse Aquatics? Charterhouse Aquatics offers a wide range of ATO systems, including: • Basic Float Valve Systems • Electronic Optical Sensor ATOs • Dual-Sensor ATOs with Fail-Safes • Advanced Auto Top-Up Systems with App Control Brands available include Tunze Osmolator, AutoAqua Smart ATO, XP Aqua Duetto, Neptune ATK Auto Top-Off Kit, and more.

5. Can I use an Auto Top-Up system on both freshwater and saltwater aquariums?

Yes! Auto Top-Up systems are suitable for both freshwater and marine aquariums. However, they are especially important in saltwater and reef tanks, where consistent salinity is critical for coral health and fish wellbeing.

6. Is it easy to install an Aquarium Auto Top-Up system?

Absolutely. Most ATO systems sold by Charterhouse Aquatics are designed for easy installation with plug-and-play functionality. They typically come with mounting brackets, tubing, sensors, and a pump. Comprehensive instructions are provided, and our support team is always available to assist.

7. What equipment do I need to use an Auto Top-Up system?

Most ATO systems include everything you need: • Sensors or switches • Pump • Tubing • Mounting brackets You’ll also need a reservoir to hold your top-up water (RO/DI water is recommended for marine aquariums). Charterhouse Aquatics offers a selection of ATO reservoirs if you need one.

8. How often do I need to refill the Auto Top-Up reservoir?

It depends on your aquarium’s evaporation rate, tank size, and ambient conditions. Typically, you’ll need to refill the reservoir every few days to once a week. A covered tank reduces evaporation and extends the time between refills.

9. Are Auto Top-Up systems safe to use?

Yes! Modern ATO systems come with built-in safety features such as: • Dual sensors • Overfill protection • Alarms for low water levels or sensor failures • Fail-safe timers Brands like Tunze, Neptune Systems, and AutoAqua prioritize reliability and safety in their designs.

10. Which Auto Top-Up system is best for my aquarium?

The best ATO system depends on: • Tank size • Sump or display tank setup • Your budget For expert recommendations, contact our experienced team at Charterhouse Aquatics, or explore customer reviews on our website to help you decide.

11. What is the difference between float switch ATOs and optical sensor ATOs?

• Float Switch ATOs: Use mechanical floats to detect water level changes. Reliable and affordable, but prone to mechanical wear over time. • Optical Sensor ATOs: Use infrared sensors for more precise water level detection. These systems often include fail-safes and are less prone to mechanical failure.