That's what I do. The instructions on the Gro2Max package say to keep in a dry area out of direct sunlight and humidity between 33F and 103F. Sometimes it can get hotter and colder than that here. I deem the refrigerator safe, and that way I know where it is.
Room temperature will work if it...
You can refrigerate what you don't use and periodically put some in their water, perhaps weekly.
Is your water city/county water with chloramines or from a chlorinated well?
That can kill the bacteria in the probiotics.
I highly recommend Gro2Max powder. It consists of beneficial bacteria and...