Have a 26 gallon tank holding RO water but about I get to the bottom it's slimy even with cold temps and enough air stones my question is is there something I can put in my water to solve it
I'll leave the suggestions for what you can put in your "water to solve it" to those who actually use something to prevent issues other than a healthy nutrient regime, but to answer the thread title:
If it's in a food grade container and air tight it should stay good for awhile I use ro water and fill around 8 5gallon sparklet jugs up and they stay fresh for over two weeks