Granular Ferric Oxide (GFO) Instructions

GFO

Purpose of GFO:

Inhibit algae growth by removing phosphates from the aquarium.

 

Granular GFO

  • Start with 1 tablespoon per 4 gallons of water
    (16 tbsp = 1 cup).
  • After 4-8 weeks the aquarium will have adjusted to lower nutrient levels and the amount of GFO can be increased up to 2 tablespoons per 4 gallons of water.

 

HC GFO

  • Start with 1 tablespoon per 8 gallons of water
    (16 tbsp = 1 cup).
  • After 4-8 weeks the aquarium will have adjusted to the low nutrient level and the amount of GFO can be increased up to 2 tablespoons per 8 gallons of water.
  • Change all both types of GFO when phosphate levels rise, typically 4-8 weeks.

 

For use in a filter bag:

  1. Pour the GFO into the bag and close securely
  2. Rinse with RO water or place under a faucet until the water runs clear
  3. Place in a high flow area of the tank or sump to maximize water flow through the GFO
  4. Change the media when phosphate levels rise or algae growth becomes visible (4-8 weeks)

 

For use in a media reactor:

  1. Place GFO in suitable reactor
  2. Place the reactor's return line into a bucket or sink
  3. Turn on the feed pump to flush the fines from the GFO until the water runs clear
  4. Place the return line in the tank
  5. Reduce the flow through the reactor so the GFO barely tumbles on the surface. 
  6. Do not allow the material to vigorously tumble.
  7. Change the media when phosphate levels rise, typically 4-8 weeks.

 


 

Special note on algae outbreaks: GFO will not solve an algae outbreak by itself. If an algae outbreak is apparent attack it head on. Manually remove algae, use GFO, add predators such as tangs, snails or hermits, shorten lighting periods, conduct proper water changes, and carefully monitor the food added to the tank. Any one of these on their own will help with algae problems, but rarely solve the problem by itself. It typically takes a combination of these approaches to eradicate an algae outbreak.