Phosphate (PO4) is directly related to algae outbreaks and coral health as lower phosphates (<0.03 ppm) usually mean less algae outbreaks and healthier corals. I say “usually” because every tank is different. Some tanks do well on lower phosphates, some do not (Hint…Chemistry and Tank Automation Program participants…this is right up your alley.)
On all my tanks and on my client builds, I always have at least one method of phosphate control running at all time with the most common method being phosphate removing media placed in a reactor.
I’ve used lots of phosphate removing medias and these are my experience with the three most common ones: RowaPhos, PhosGuard and Granulated Ferric Oxide (GFO).
RowPhos or “rowa” for short is widely used in Europe. Availability in the USA is somewhat limited as I don’t see it in local fish stores as much as the other two products I’ll cover. RowaPhos is a small sized media that comes in a bag. That bag is placed in your tank or sump. Any attempt I’ve tried to remove the media from the bag and place it in a reactor hasn’t worked as the particle size of RowaPhos is small which means the media blows out of the reactor. Just placing the bag of RowaPhos in the reactor is very inefficient as most of the water flowing through the media bypasses the bag and little or no phosphates are absorbed. Because of the higher cost due to import duties, the inability for me to buy it in bulk, and since it doesn’t work well in a reactor, I don’t use RowaPhos in my tanks.
PhosGuard is an aluminum oxide product made by SeaChem. The media looks like small white balls and the balls are large enough to be placed in a media reactor and not get blown out of the media reactor. PhosGuard is available in bulk which is great for large tank guys like myself.
Hobbyists will often get up in arms about PhosGuard as it is an aluminum based product and is rumored to leach aluminum into your tank water. Aluminum is also thought be harmful to corals hence the concern for those of us with reef tanks. SeaChem released a research paper on the solubility of aluminum oxide and concluded that “The results of these experiments show that under reef conditions (pH near 8) there is no detectable soluble aluminum released from alumina. Under conditions of low pH and high dosage levels, soluble aluminum can be released from alumina; at three times the label dosage rate, we detected 0.2 mg/L aluminum at a pH of 5.3.” (full paper here)
Here’s a hint…if the pH gets to 5.3 in your reef tank, your coral and your fish, will be long since dead.
I personally don’t use PhosGuard in my tank as Granulated Ferric Oxide (GFO) absorbs much more phosphate. If you can’t get your hands on GFO, then PhosGuard is a good alternative.
Granulated Ferric Oxide (GFO)
GFO is an granular iron based product and is widely used for phosphate control due to it’s low price, widespread availability and high absorption capabilities. It comes in several grades and my experience has been that the “regular” grade works fine. Therefore, I don’t recommend the higher capacity GFO products.
GFO doesn’t come without drawbacks though. It can easily clump up in a media reactor and must be thoroughly rinsed before being placed in your systems.
Since I can easily buy it in bulk at an affordable price and I’m ok with the added maintenance of GFO, I use regular grade GFO on my tanks.
Phosphates are a parameter I monitor in my tanks and phosphate absorbing medias are the easiest way I’ve found to keep my phosphates in check.Browse the Store! Questions?