Im not for sure the reason. But it needs to tumble so that the small gfo
particles dont clump. Carbon needs to be more packed bc it grinds away to dust. Make sure you rinse the gfo
dust before you have it cycle your system. I use a milk jug and let the pump suck water out of the tank into the jug. Then dump the water out in the sink. This makes sure you dont get dust in your tank. The life of gfo
is suppose to be 4 to 6 weeks some people even use it up to 8 which should be you max if you do that. Ive recently bought something else to put in my reactor its called rowaphos I think does the same thing. But it wont leach the phosphates back into the water. Which the gfo
media can possibly do. Its all about what you prefer. Im trying it to make a decision in whats best for me. Hope this helps.