Water Question?????

So I'm doing a smallish indoor grow. I'm growing in soil and using a 32 gallon container to use as a reservoir so I don't have to mix solutions so often. Thing is, I've been letting the water sit in there in order to let the chlorine dissipate. But after a few days the water starts to smell real bad. I read somewhere that the smell is due to unhealthy Anaerobic bacteria, and that of one added an air stone, the good and healthy Aerobic bacteria would take back over. Has anyone dealt with this? I'm about to go buy a little air pump and see if it helps. How do others maintain healthy res water?

32 gallons you're going to want more than a 'little' air pump, at least get one with dual outlets so you can have 2 stones.

If you're doing organics\all natural in particular (what plant food are you using?) you can't let mixed ferti solution sit around for more than a day or two. Even aerated I wouldn't use it after 3 days.

I'm using General hydropinics: Flora micro, grow, and bloom. So I'm curious about what you wrote. If you cant let your nute solution sit around, then what do these hydro guys do? Most don't change there rez's but for every couple weeks or so. How do their rez's stay fresh? I'm going out of town for a few days and my friends is gonna water my babies. So I need an ample supply of nutrient solution to get me through while I'm gone.