I recieved a bag of PuriResin (I think it's just GFO) for free through an Amazon program called Vine. I thought it would come in a mesh bag where I could remove some of the GFO in order to get the right amount for my 20 gallon reef, but the bag is a sealed cloth pouch. One bag treats 100 gallons. What's the protocol here? Do I put an oversized bag in or do I reduce the contents? A quick Google search gave mixed results ranging from it should be fine to it will kill all my corals.