NT Labs Test Phosphate (PO4) is an aquarium water testing kit used to measure phosphate (PO₄) levels in freshwater or marine tanks.

What is phosphate?
Phosphate is a naturally occurring compound that enters the aquarium through fish waste, uneaten food, and decaying organic matter. While small amounts of phosphate are normal, excessive phosphate levels can contribute to poor water quality, which results in unwanted algae growth. In reef aquariums, high phosphate levels may also inhibit coral growth and affect coral health.

Phosphate is invisible to the naked eye, so regular testing is important to maintain a balanced and healthy aquarium environment.

What is the recommended phosphate level?
For freshwater aquariums, phosphate levels should generally be kept below 1.0 mg/L (ppm) to help control algae growth.

For marine and reef aquariums, the ideal phosphate level remain below 0.03 – 0.1 mg/L (ppm), as corals and sensitive marine organisms require very low phosphate levels for optimal health.

What do I do if the phosphate level is wrong?
If phosphate levels are too high, perform partial water changes and reduce overfeeding or excess waste buildup in the aquarium. Cleaning the substrate and filter regularly can also help lower phosphate levels.

Phosphate-removal media may help maintain lower phosphate levels, especially in reef aquariums.

If phosphate levels remain consistently high, it is important to check feeding habits, source water quality, and overall aquarium maintenance routines.

How to use?

- Ensure the test tube is clean.
- Take a 5 ml sample of water into the test tube.
- Add the recommended number of drops of the Phosphate reagent.
- Replace the test tube cap and shake thoroughly.
- Wait the instructed development time, then compare the colour of the sample to the colour scale provided.
- Lower phosphate levels are represented by lighter colours, while darker colours indicate higher phosphate concentrations.
- Any colour forming after the recommended waiting time should be ignored.