Does bleach accumulate in water, or does it naturally evaporate or break down with time?
I have an ebb and flow indoor hydroponics system for watering my plants for weeks while I'm away on travel. I have a 5 gallon tank that contains the water, and a large flow tray contains my plants.
Since this system has to work without attendance for potentially months, mold and algae buildup is a serious concern. To mitigate these, the tank and flood tray are opaque, so no light can get into them (except the top of the flood tray where the plants stick through).
From various hydroponics forums, I've read bleach is a common and effective mold and algae retardant when used sparingly. The amount I use is 1 tbsp per 5 gal. I've been using this for a few months now, and my plants are doing well, and I've seen no mold or algae growth.
However, I lose about 1/4 gallon of water per week due to evaporation and absorption by my plants. When I add more water, should I add the proportional amount of bleach? Or is the bleach I've already added still in the remaining water?
Obviously, too much bleach will kill my plants in addition to mold and algae, so I want to make sure I'm only adding enough that's appropriate and that it's not building up to a fatal concentration.
