My thoughts on this subject: I airate mine becouse I prefer to be on the safe side. I use a reed switch to a 5 gal bucket under the tank stand and a small pump to deliver the water to the tank. To this I ad kalk, and I have witnessed Kalk begin to take on a smell when left for extended periods in a container. Also as pump delivers water to the tank, I have a small hole drilled just above the water line in the return at the tank to make for a siphon break when the pump stops. This couses a vacuum in the line sucking in air and I am sure some small amount of tank water must get returned to the bucket with it. This would contaminate the top off water.
Keep in mind that if you are dosing Kalk, it loses it's effectiveness after just a couple days. If you are putting Kalk in this water and then storing it, you are just wasting Kalk.
Not dosing kalk, I have a Ca reactor for that. The RO/DI water is strictly being used to top off evaporation. When my reed float switch, located in the sump, kicks off the pump in the container, the water goes from the storage tank in the basement up into the sump.
Any one have any thoughts on aerating their top off water? I have my RO/DI water for top off in a 35 gallon Rubbermaid container. I have pump in the container, controlled by a float switch, that pumps any water needed for top off. I only have to fill up the top off water every 2-3 weeks. Is it ok to leave water stagnant for a week or two? What would happen to it if it is not ok? Maybe I should put a small powerhead in with the top off water?
