Granular Ferric Oxide (GFO)

Granular Ferric Oxide (GFO) should be used as a part of your tank filtration tools primarily to control phosphate levels. Excess phosphate is one of the main contributors to algae growth, which can quickly become a major problem in a marine system. Controlling your phosphates helps stem current algae issues and prevents future algae outbreaks. 

🧲 Benefits of Using GFO

1. Removes phosphate (PO₄³⁻)
   GFO chemically binds with phosphate in the water, effectively removing it from the system and locking it away.

2. Helps control nuisance algae
   Algae like hair algae, bryopsis, or cyanobacteria thrive on phosphate. Lower phosphate = less algae.

3. Supports coral health
   High phosphates can inhibit calcification in stony corals (SPS/LPS), making it harder for them to build their skeletons. Keeping phosphate low improves coral growth and coloration.

4. Reduces Tank Maintenance time
   Reducing phosphates in your tank helps control algae, thereby reducing the time spent cleaning your tank glass. 

STARTING INSTRUCTIONS

Measure out the amount to be used in your tank. The recommended starting amount is around 1 TBSP per every 4 gallons in tank volume. Follow instructions below based on your method:

FILTER BAG

Add GFO to your filter bag. Rinse the bag with water from your tank or RO/DI water about 30 seconds, or until the water runs clear. Place the bag into your sump or a high flow area of your tank to ensure water is being filtered well through the GFO. Regularly test your tank phosphate levels to ensure GFO is replaced when phosphate levels start rising. 

MEDIA REACTOR

Add the measured GFO to your media reactor. Fill a large bucket with fresh or RO/DI water and place your media reactor’s feed pump in the bucket, and the reactor outlet in a sink. Pump water through the reactor for about 30 seconds, or until the water runs clear. Water entry speed should gently tumble the GFO to avoid pulverizing the media. Carefully dispose of any water remaining inside the reactor before installing. 

MAINTENANCE INSTRUCTIONS:

Phosphate levels may increase rapidly during first time use - monitor with a test kit during the first week used. Replace GFO once phosphates begin to rise after initial use. GFO can be replaced every 4-8 weeks after the initial change, or as needed if phosphate levels begin to increase.