The proper way to use Phosguard is to just toss some in a filter bag, rinse it in the sink good before you use it (it gets hot and crackles like rice crispies), and then put it in a place that will get flow through it for about 3 days and then take it out.. that is the "proper" way to use it, although my friend puts it in a reactor and uses it 24/7 for over a month and it still works great after a months use. The aluminum it releases back into the tank is the problem people have issues with, and I have seen the "studies" written on it, but to me there is a big difference between a perceived problem that a scientest says could happen and actual real life reports from reefers that had a real problem due to using it. Not that it can't happen, but I have not witnessed a single problem from using it so far, but I also don't have a ton of experience with it to make a claim it is 100% safe to anyone to use 24/7 so you have to decide if the risks are worth the benefits.