Dosing Lanthanum Chloride to reduce PO4

[xenon]

I have a 1,200g fish system that costs us a small fortune in GFO.

I am just looking for feedback on what products you guys use and how exactly do you use it?

I have a jug of Sealer that I was planning to dilute to 1ml into 1000ml. Then dose it automatically via dosing pump directly into my 4' MRC Orca Pro III skimmer and have a 10 micron filter sock on the output of the skimmer.

The main question is how often will the filter sock need to be replaced?

I am also interested in products like Agent Green. ATM says its safe to dose to your tank without the need of any filter socks?