stinky water??

what would cause my water in my reservoir to be stinky after 2 days?? i have well water and have added no nutes yet because i would like to get this figured out first, also my ph goes up everyday so im using ph down everyday?? got me stumped honestly?

U have some funk growing in ur res. Is it light proof and what temps do u have in ur res? I would drain and clean out res...rince off roots as well