Understanding and Managing Harmful Substances in Aquariums: A Guide to Effective Water Treatment
Aquarium maintenance is more than just feeding your fish and ensuring their environment is visually pleasing. It’s a delicate science of maintaining water quality, which is crucial for the survival and well-being of aquatic life. Harmful substances such as ammonia/ammonium, nitrite, and heavy metals can accumulate in aquariums, threatening the health of your aquarium’s inhabitants. In this guide, we will explore these harmful substances, how to manage them with products like Quantum Aqua’s Water Primer™, and critical precautions involving oxygen and pH levels.
What Are These Substances and What Do They Do?
Aquarium water is a micro-ecosystem, and several harmful substances can disrupt this balance if not properly managed:
Ammonia (NH₃) and Ammonium (NH₄⁺):
- Source: These compounds originate from fish waste, uneaten food, and decaying organic matter.
- Why They’re Dangerous: Ammonia is toxic, even in small concentrations. It affects the respiratory system of aquatic animals, leading to gill damage, stress, and death.
- Behavior: Ammonia’s toxicity is influenced by pH. At higher pH levels, ammonium converts to ammonia, increasing the risk to fish. Quantum Aqua’s dosing calculator has a helpful quick calculator to determine this.
Nitrite (NO₂⁻):
- Source: Nitrite forms during the nitrification process, where beneficial bacteria convert ammonia into nitrite.
- Why It’s Dangerous: Nitrite interferes with oxygen transport in fish by oxidizing hemoglobin into methemoglobin, causing “brown blood disease.”
Heavy Metals (e.g., Lead, Copper):
- Source: Tap water can introduce heavy metals into aquariums, particularly in areas with aging infrastructure or hard water, some supplements may also contain heavy metals.
- Why They’re Dangerous: Heavy metals are toxic at low concentrations, damaging fish kidneys, nervous systems, and other organs.
Chlorine and Chloramine:
- Source: Municipal tap water contains these chemicals as disinfectants.
- Why They’re Dangerous: Both are highly toxic to fish and beneficial bacteria in your aquarium, disrupting the biological filtration process.

How Water Primer™ Helps Remove These Substances
Water conditioners like Quantum Aqua’s Water Primer™ are invaluable tools for hobbyists. Here’s how they address specific challenges.
Treating Tap Water:
Tap water contains chlorine and chloramine to render it safe for drinking, but these are not suitable for your aquarium. Water Primer™ neutralizes these chemicals, making tap water safe for aquariums.
How It Works:
- Neutralizes chlorine and chloramine.
- Binds heavy metals, rendering them harmless.
- Prepares tap water for immediate use in freshwater and saltwater aquariums.
Usage Tips:
- Add 5mL per 300L (79 US gal) of tap water.
- If chlorine levels are high, a double dose may be used.
Emergency Situations:
Ammonia and nitrite spikes can occur due to overfeeding, fish deaths, or filter failure. Water Primer™ detoxifies ammonia and nitrite, helping to prevent fish stress.
Emergency Usage:
- Add up to 25mL per 300L (79 US gal) directly to the aquarium in high flow area.
- Aerate the aquarium to ensure adequate oxygen levels during treatment to assist in the nitrogen cycle.
The Role of Oxygen Levels
Oxygen levels play a crucial role in aquarium health, especially during water treatment.
Why Oxygen Matters:
- Beneficial bacteria that process ammonia and nitrite require oxygen.
- Low oxygen levels can hinder the nitrification process, leading to a build-up of toxic substances.
Precautions During Treatment:
- Increase aeration during water treatment by using air stones or adjusting your filter’s output.
- Avoid overusing conditioners, as they can temporarily deplete oxygen while neutralizing chemicals.
Pro Tip: Always monitor oxygen levels, especially in densely stocked aquariums or during warm weather when oxygen solubility decreases.

Managing pH Levels
The relationship between pH and ammonia toxicity is a critical consideration in water treatment.
The pH-Ammonia Connection:
- At low pH (<7.0), ammonia exists predominantly as ammonium (NH₄⁺), which is less toxic.
- At high pH (>7.0), ammonium converts to ammonia (NH₃), increasing toxicity.
Potential Risks:
- Using a water conditioner that affects pH can inadvertently increase ammonia levels if pH rises suddenly.
- Rapid pH swings can stress fish and harm sensitive species like shrimp or corals.
Precautions When Adjusting pH:
- Test water parameters before and after treatment.
- Make gradual pH adjustments using buffers or conditioners designed for aquarium use.
- Monitor ammonia/ammonium levels after any change in pH to ensure no harmful spikes occur

Maintaining a healthy aquarium requires vigilance and an understanding of water chemistry. Harmful substances like ammonia/ammonium, nitrite, and heavy metals can quickly threaten the balance of your aquarium, but tools like Quantum Aqua’s Water Primer™ can help mitigate these risks effectively.
However, treatment requires attention to details such as oxygen levels and pH, as mishandling these factors can exacerbate the very problems you’re trying to solve. By following best practices and understanding the chemistry of your aquarium, you can ensure a thriving environment for your aquatic friends.
Remember: Always prioritize testing, monitoring, and gradual changes to maintain stability in your aquarium. Your fish and corals depend on it!
Happy Aquarium-Keeping!
Authored and Designed by Jordan Kambanis - Chemical Engineer, BEng (Hons) in Chemical & Biomolecular Engineering, BSc in Chemistry