FAQs – GFO, Phosphates and Algae
What is Granular Ferric Oxide used for?
GFO or Granular Ferric Oxide is designed to remove phosphate (and other metals) from bodies of water – in municipal systems its main use is for the removal of arsenic from water that will be consumed by humans. PHOSFOE© is deployed in municipal treatment plants in the UK & Europe.
Why use GFO in Aquariums (and ponds/swimming ponds)?
While phosphorous is required for fish, corals, and beneficial bacteria to grow and thrive in your reef tank, it should not be allowed to stack up in the aquarium water as a byproduct. Managing phosphates is all about balance and stability, finding the right level that works for your particular tank, and not allowing the levels to constantly rise. You don’t want to starve your water of phosphate altogether, but you also cannot let it rise out of control.
GFO can be used as a tool or treatment to lower elevated phosphate levels but is also safe for everyday use in aquariums with a heavy bio-load where phosphate levels cannot be managed by other means of filtration.
Each tank is of course different and unique in terms of the ideal phosphate level. Most tanks ranging from 0 to 2 years old should be maintaining a lower phosphate level between 0.01 – 0.04 PPM for the best results. More mature aquariums that have been established for 2 – 3 years or more with large mature coral colonies can often run with higher levels of phosphate input without issue.
What does it mean when I have elevated phosphate levels?
Elevated phosphate levels often indicate an elevated nutrient level altogether. This means nitrate is likely on the rise as well and you should be mindful of your bio-load. Nutrients like this can contribute to the growth of nuisance algae and various other pests (cyanobacteria, dinoflagellates, etc). Phosphates can inhibit calcification among corals, meaning it will limit their growth at higher concentrations. On the other hand, if your tank is stripped of phosphate altogether, you can encounter bacterial imbalances and starve your corals and other critical organisms of necessary phosphorous
Where does Phosphate come from?
The main source of phosphate is going to be fish and/or coral food and the resulting waste. Additives and media can also contribute, but the amount will often be negligible compared to what your food is bringing in. Managing filtration that helps remove leftover food and fish waste is your primary focus for phosphate control, should that not suffice.
GFO will not solve an algae outbreak by itself. If an algae outbreak is apparent, attack it head-on with a multi-prong defense specific to the type of algae you’re dealing with.
How do I maintain crystal clear aquarium water? (And pond or swimming pond water)
Here are some common ways of helping defend your tank (and ponds or natural swimming pools) against nuisance algae growth. Algae is a natural part of keeping an aquarium and incorporating these methods into your regular routine will ultimately help you avoid problems with excessive algae.
- Manual removal and cleaning of algae-covered surfaces
- Use GFO or other methods to maintain low phosphate levels
- Add utilitarian fish and clean up crew animals such as tangs, blennies, snails, and crabs
- Shorten lighting periods or perform a blackout period
- Maintain a more efficient water change schedule and proper filter maintenance
- Maintain and tune your protein skimmer
- Monitor the tanks nutrient input via fish and coral foods