pgravis
Well-Known Member
GFO
What is it?
GFO, or Granulated Ferric Oxide, as the name implies, is an oxide of Iron (remember from chemistry class, an oxide is a compound that contains oxygen) or in layman’s terms a type of Iron. It is also considered to be rust. It has many uses, some of the major ones being in the Iron industry to make steel. It is also used as a polisher/sharpener, a pigment (sometimes used in cosmetics), in tape recordings, and of course, in the aquarium industry.
Why we use it
Without going into a chemistry lesson, the reason we use GFO is to remove Phosphate from our tanks. It does this through a chemical reaction in which phosphate binds to the GFO, removing it from the water column. It will also bind other organic compounds, and some say will even bind certain metals, thus removing them from the water column.
How we use it
There appears to be two main ways of using GFO. The most popular (and it seems preferred) method is using it in a reactor. A reactor pumps water from the aquarium into a tube of acrylic, gently tumbling the media (in this case GFO), keeping it suspended in the water column. This method is preferred because it increases the surface area of GFO that the water is exposed to, thus increasing the amount of phosphate it can bind to. The other method is more rudimentary, and uses a filter sock placed in an area of the tank (or sump) that has a higher flow. There are a couple of disadvantages to this method. Because the GFO is packed into a filter sock, the amount of surface area is severely limited. Also, it must be a fairly small fine mesh sock that is used, as it can seep through bigger openings and spread through the display tank. Many seem to use pantyhose as a substitute for the more common filter socks. Another problem encountered while using this method is caking. Caking is when the GFO forms a compact, brick like structure, which again, limits the surface area being exposed to the tank water. The one advantage to the filter sock method is the price.
Potential Problems
Adding GFO too quickly to your aquarium can cause issues. Some report coral stress, tissue recession, and bleaching. It doesn’t appear to be widely understood why this happens, but it appears most think the rapid depletion of phosphate shocks the system. It also is believed the GFO may bind with trace minerals that coral need to survive, and because of the sudden drop in available minerals or nutrients, the coral becomes stressed. This all being said, it appears most overwhelmingly think the benefit outweighs the risk of using GFO, with the caveat to go slow and gradually increase the amount of GFO you are using.
How much to Use and special instructions
The amount of GFO that is needed is roughly one tablespoon per four gallons of water.
However, the simplest way to calculate how much is needed is to find a reef calculator, such as the one found here ([url]http://www.bulkreefsupply.com/store/reef-calculator[/URL]).
Also, before using GFO, it is important to rinse it in RO water to remove the dust.
Sources:
www.wikipedia.org
Iron Oxide Hydroxide (GFO) Phosphate Binders by Randy Holmes-Farley - Reefkeeping.com
www.bulkreefsupply.com
My own experiences, and those on my local forum!
What is it?
GFO, or Granulated Ferric Oxide, as the name implies, is an oxide of Iron (remember from chemistry class, an oxide is a compound that contains oxygen) or in layman’s terms a type of Iron. It is also considered to be rust. It has many uses, some of the major ones being in the Iron industry to make steel. It is also used as a polisher/sharpener, a pigment (sometimes used in cosmetics), in tape recordings, and of course, in the aquarium industry.
Why we use it
Without going into a chemistry lesson, the reason we use GFO is to remove Phosphate from our tanks. It does this through a chemical reaction in which phosphate binds to the GFO, removing it from the water column. It will also bind other organic compounds, and some say will even bind certain metals, thus removing them from the water column.
How we use it
There appears to be two main ways of using GFO. The most popular (and it seems preferred) method is using it in a reactor. A reactor pumps water from the aquarium into a tube of acrylic, gently tumbling the media (in this case GFO), keeping it suspended in the water column. This method is preferred because it increases the surface area of GFO that the water is exposed to, thus increasing the amount of phosphate it can bind to. The other method is more rudimentary, and uses a filter sock placed in an area of the tank (or sump) that has a higher flow. There are a couple of disadvantages to this method. Because the GFO is packed into a filter sock, the amount of surface area is severely limited. Also, it must be a fairly small fine mesh sock that is used, as it can seep through bigger openings and spread through the display tank. Many seem to use pantyhose as a substitute for the more common filter socks. Another problem encountered while using this method is caking. Caking is when the GFO forms a compact, brick like structure, which again, limits the surface area being exposed to the tank water. The one advantage to the filter sock method is the price.
Potential Problems
Adding GFO too quickly to your aquarium can cause issues. Some report coral stress, tissue recession, and bleaching. It doesn’t appear to be widely understood why this happens, but it appears most think the rapid depletion of phosphate shocks the system. It also is believed the GFO may bind with trace minerals that coral need to survive, and because of the sudden drop in available minerals or nutrients, the coral becomes stressed. This all being said, it appears most overwhelmingly think the benefit outweighs the risk of using GFO, with the caveat to go slow and gradually increase the amount of GFO you are using.
How much to Use and special instructions
The amount of GFO that is needed is roughly one tablespoon per four gallons of water.
However, the simplest way to calculate how much is needed is to find a reef calculator, such as the one found here ([url]http://www.bulkreefsupply.com/store/reef-calculator[/URL]).
Also, before using GFO, it is important to rinse it in RO water to remove the dust.
Sources:
www.wikipedia.org
Iron Oxide Hydroxide (GFO) Phosphate Binders by Randy Holmes-Farley - Reefkeeping.com
www.bulkreefsupply.com
My own experiences, and those on my local forum!
