I had this ac200 that was running on my 20gal. I sold the tank a few weeks ago and kept the ac200. I rinsed it and left it in a bag untill today. I wanted to switch it for the ac150 on my 10gal to get more filtration. So when I took the filter out the bag I saw tiny grey snails in the bottom of the filter. I even found smaller ones embedded in the sponge. I rinsed the filter and sponge and threw out the carbon bag. So where did they come from? I heard that snails are a serious problem. I didnt set up the filter caus I was paranoid so I put it back in a plastic bag. What precautions should I take to make this filter safe to use?