I have a subscription to algae barn for pods and phyto that arrive once a month. I started dosing a few months back when I needed to beat by dinos. My tank isn't that big so I don't dose the phyto that much like maybe 5 ml a day before leaving for work. I wanted to know does Phyto have an expiration if I don't use it all? Cause I now have two bottles that I have not finished using and I'm wondering if I am wasting my money.