Magna HCR GFO

[BaliReefBox]

Hi I have a DIY reactor that I made from a water filter cannister and small DC pump. My Phosphate was at 0.58 (hanna checker) so I decided to try a mix of GFO and activted carbon. I mixed 100ml of carbon and sprinkled 1 Tblespn of GFO as I loaded the carbon so as to spread it through the cannister. I tested the water again this morning and the phos was down to 0.21. a few how later I have this incredible rusty mess in the reactor, my filter sock in caked in brown rust deposits, the glass and AIO have a film on them and the wated is as cloudy as. I removed the Gfo, changed the sock added fine floss over the sock and fill the reactor with just new carbon. Now my question why did all this happen? I read that the water may go cloudy for a bit but this was extreme. I appreciate the GFO will rust but to the extent of brown deposits every where? Is it just this brand of GFO? I have ordered Rowaphos to try it. Has any one experienced this with Rowa.
Thx for the help

 

[BaliReefBox]

OK well about 2 hrs later after changing the sock, cleaning the rings and adding filter mesh the water has cleared up, mostly and the gunk is here. The sand had a brown film on it which came off with a squirt from the baster. Glass still has a film on it as does the entire AIO sump. I will clean the glass tomorrow and do a 20% water change also.
Does all GFO do this or is it just the rubbish one I bought?