I always think bubbling is a good idea, helps keep the solution fresh and mixed, adds dissolved oxygen, and maybe keeps the anaerobic bacteria from taking hold. Maybe add some beneficial bacteria to the mix. I just hand water, drain to waste, but my solution stayed fine for 3 days at least. BUT I was using citric acid as a ph down and was having to adjust the PH before every feed. Bubbling your nutes will constantly raise the PH.