[jdieck]

I had the opportunity to run a comparison test between what at the time (last year) I considered the three most used and available Iron Oxide Hydroxide based media, Phosban from TLF, Rowaphos from Rowa and PHOsR from Warner Marine.
Since then there has been other medias available that may or may not be better, I even found one that claims to be regenerable.
In any case these are my observations.

a) Physical: As mentioned above PHOsR comes on a pelletized form while Rowa and Phosban come in irregularly shaped grains.
Rinsing the media is important so my observation was that Rowa and phosban have a lot more fines requiring a significant more rinsing than PHOsR.

b) Adsorption:
In adsorption tests Rowaphos showed to be the one that adsorbed the most phosphate (2 to 3 times more than Phosban or PHOsR) in less than half the time. This effectiveness seems to be a potential reason why there seems to be more claims of sudden shock with Rowa than with other medias so if using rowa it is advisable to start with small quantities and increase as the phosphate level increases.

Now having said that in long term tests the media that lasted longer and in total ended up adsorbing more was the PHOsR from Warner Marine.
The explanation I find for this is basically that given the shape of the media, PHOsR allows a better more uniform flow throughout the media effectively using all of it. Rowaphos and Phosban have a marked tendency to get channeling in the reactor and to clump together easier thus blocking the flow and coating some of the grains making the media unable to be fully utilized.

c) Having the initial results and decided on using PHOsR I tested it's potential for creating undesirable reaction in the critters, to do so I used four times the recommended quantity to see if it had some effect on the critters. The only result was that the media lasted more than eight months and mini-stars, worms, feather dusters and snails started living in the reactor for which I could conclude that the media is really safe to use if fines are not allowed to pass into the system.

For the Phosphate testing I used a colorimeter and for short term adsorption I used a standard phosphate solution of 1 ppm, all equipment between tests was cleaned using high purity hydrochloric acid.

Since the time of my tests Warner has come out with a new media PHOsR HC that although not pelletized is claimed to adsorb three times more than regular PHOsR and to be less prone to break apart and with higher density so higher flow could be used in the reactor.