Phosphate Removal

[mindi]

Not sure if right place for this..? The answer will be chemistry though rather than the question.
I currently use Brightwell Phosphat-E and my Deltec skimmer to manage phosphates and have consistent readings of 0-5 ppb on my Hanna ULR Phosphorus Checker. Why do people use reactors and GFO type media..? I suspect I am missing something. Am I just doing it a more expensive way in the longer term, or am I experiencing side effects I am not realising. Most people seem to use reactors so I guess I want to understand why, and if I should change. If it is purely a cost thing then one 500ml bottle of Phosphat-E ($40) treats my 100G mixed reef for 12 months. Genuine question, I am in no way arguing for my current approach over a reactor.

[dkeller_nc]

There's a few reasons why folks would choose GFO media over Lanthanum Chloride (which is what Brightwell's Phosphate-E is). The first is the potential danger of Lanthanum compounds to certain species/genuses of fish. Tangs of the Zebrasoma genus are apparently particularly sensitive to lanthanum chloride and/or the lanthanum phosphate precipitate that is formed when LaCl3 is dosed, and it's possible to kill fish of this genus by even moderate doses of LaCl3.

Because of the above, folks that use LaCl3 typically find it necessary to dose the compound into a very efficient mechanical filter - many use low-micron rated filter socks for this purpose, which will clog very quickly if left in the system after the LaCl3 dosing operation is completed.

Finally, because one doesn't want excess LaCl3 in the system, most that use it need to carefully calibrate the amount that they use to the free phosphate concentration of the water - you want an excess of free phosphate to ensure that all of the LaCl3 gets converted to lanthanum phosphate and immediately precipitates.

GFO, by contrast, doesn't appear to have any toxic effects on the various creatures that we typically keep. And for the most part, it's a "set and forget" type of operation where one puts a measure of the solid GFO in a reactor, and only changes it when fairly infrequent phosphate tests indicate that the media is exhausted. Finally, GFO can be regenerated with inexpensive chemicals (principally sodium hydroxide solution made from cheap lye, possibly an initial dilute hydrochloric acid wash), so the overall expense is relatively low.

[mindi]

Thank you very much for your answer sir. Much appreciated.