I purchased 4oz Fritz Turbo 900 at LFS, all of their stock bottles had a best used by date of 12/7/21. I research and found that it has a 6ish months shelf life refrigerated. now is 8/7/21. It smells really funky, but I use it anyways. is this something I should be worried about? I'm planning to set up a 10g QT tank too and if I should use the leftover?