I know nutes go bad but could you rig up a air pump and stone to keep so low dose nutes in the system so they won’t go bad? If it’s just for water I don’t see much advantage because of adding nutes to feedings. Also with the little water they use you would still have to flush to get tensing nutes out so they don’t build up and cause problems later in the grow. I like the idea just not sure how the nutes would work. 
What is it?
Yes you can but don’t leave more the 2.5week then change don’t mix up go much I do 25l of water then mix my nutes but I have a few plant do that is done in 3 days