I read here that LACL irritates tangs. I have a powder blue and a hippo tang, and do not want to add anything that will bother them. So I plan to stick with the GFO only. I'll definitely let you know how it goes.You will need a lot of GFO. I was going through 1kg every 3-4 weeks on my 120G just to MAINTAIN the PO4 under 0.1ppm for the past year or so. Anything higher than 0.1ppm was brought down diligently, cheaply with TM Elimi-Phos Rapid (Lanthanum Chloride) dosed directly into the neck of the skimmer. Do let us know how it goes?