Air Quality Sensor

Monitoring the air around your tank is more important than you think. A rise in C0² can cause a slow drop in PH for example, letting you know when to open a window.

The come in many differnt forms and price ranges but essentially all do the same thing.

Marine assistant uses Tuya system for it wireless options, Other options work too but the guides here are based on the Tuya system.

Air quality Sensor

Wireless sensor (Tuya)

An air quality sensor for reef aquariums measures parameters like CO₂ levels, humidity, and VOCs (volatile organic compounds). It works by using chemical, optical, or electrochemical sensors to detect gas concentrations in the air. Monitoring air quality is important because high CO₂ levels can lower aquarium pH, affecting coral health. Proper ventilation and air quality help maintain stable tank conditions, especially in closed environments with CO₂ reactors or calcium reactors.

VOCs (Volatile Organic Compounds) are important to monitor around reef aquariums because they can negatively impact water quality and marine life health. VOCs are emitted from household products like paints, cleaners, air fresheners, and adhesives. When these compounds evaporate into the air, they can dissolve into the aquarium water

What is Formaldehyde and Why Is It Important to Measure Around a Reef Tank?

Formaldehyde (CH₂O) is a colorless, strong-smelling gas that is widely used in household products, adhesives, paints, and some disinfectants. It is a volatile organic compound (VOC) that can off-gas into the air and dissolve in water. In an aquarium environment, formaldehyde can come from various sources, including:

Household materials (furniture, carpets, and paint near the tank)
Aquarium treatments (some medications, preservatives, or resin-based products)
Decaying organic matter (if improperly maintained, waste buildup can contribute to VOC emissions)

Why Measure Formaldehyde Around a Reef Tank?

Harm to Aquatic Life: Formaldehyde is toxic to marine organisms, including corals, fish, and invertebrates. Even low concentrations can cause stress, disease, or death in sensitive reef species.
Water Contamination: If formaldehyde dissolves into the aquarium water, it can disrupt biological filtration and harm beneficial bacteria, leading to ammonia spikes and poor water quality.
Human Health Risks: High levels of airborne formaldehyde can cause irritation of the eyes, nose, and throat, and long-term exposure is linked to respiratory problems and other health issues.
Tank Equipment and Corrosion: Some materials in aquarium setups, such as plastic tubing and seals, may degrade faster if exposed to formaldehyde.

Safe Formaldehyde Levels

Ideal Range: Below 0.05 mg/m³ (recommended for general indoor air quality)
Concerning Levels: Above 0.10 mg/m³ (can start causing irritation and potential health risks)
Dangerous Levels: Above 1.0 mg/m³ (acute exposure can cause severe respiratory distress)

What Are VOCs and Why Measure Them Around a Reef Tank?

Volatile Organic Compounds (VOCs) are a broad group of chemicals that easily become vapors or gases at room temperature. They can come from household products, building materials, cleaning agents, and even some aquarium-related products. Common VOCs include formaldehyde, benzene, toluene, and xylene.

Why Measure VOCs Around a Reef Tank?

Impact on Marine Life: Some VOCs can dissolve into the water, potentially harming corals, fish, and beneficial bacteria in the nitrogen cycle.
Water Quality Degradation: VOC contamination can disrupt biological filtration, increasing stress and disease risk for marine organisms.
Air Quality & Human Health: High VOC levels can lead to respiratory issues, headaches, and long-term health risks for humans.
Equipment & Material Degradation: VOCs can contribute to corrosion or breakdown of certain plastics, seals, and adhesives used in aquarium setups.

Safe VOC Levels Around a Reef Tank

Ideal Range: Below 0.5 ppm (generally safe for humans and marine life)
Concerning Levels: Above 1.0 ppm (may indicate a source of pollution that could impact the tank)
Dangerous Levels: Above 10 ppm (high VOC exposure can be harmful over time)

VOCs Conclusion

Monitoring formaldehyde in the 0-10.00 mg/m³ range ensures that even small concentrations are detected before reaching harmful levels. If formaldehyde or VOCs are detected around your reef tank, improving ventilation, using activated carbon filtration, and identifying contamination sources can help maintain a safer environment for both marine life and humans.

Since VOCs cover a wide range of chemicals, the effects will depend on the specific compounds present.

Why Monitor CO₂ in the air Around a Reef Tank?

Carbon dioxide (CO₂) is a key factor in pH stability, gas exchange, and overall water chemistry in a reef aquarium. Monitoring CO₂ in the air helps prevent pH drops in the tank, which can stress corals, fish, and invertebrates.

Safe CO₂ Levels in Air Around a Reef Tank

Ideal Range: 400-600 ppm (normal fresh air levels, best for stable pH)
Concerning Levels: 600-1,000 ppm (may lead to slightly lower pH in the aquarium)
High Levels: 1,000-2,000 ppm (can cause significant pH drops and increased stress in marine life)

Hardware conection

How its conected

Hardware conection is this case is easy, ensure it is mounted in an area around the tank. I like to mount them towards the lid of the tank as this is where most of the gas exchange will take place.

I Prefer the ones that plug into a USB socket as they dont require changing batteries.

Software setup

Getting set-up

Connecting tuya devices is quite simple, you will need to download the app relivant to your sensor, For marine assistant I use Tuya devices so I use their app too. Once you have the app downloaded you will need to put the device into pairing mode and search for it in the app. Follow the instructions supplied.

Once you have it set-up in the app you can move onto adding the device into Home Assistant. First you will need to add the Tuya integration if you havent already.