Best way to keep water for auto water changes over a 2 week period?

[dpassar12]

Does it need to be mixed constantly? Normally I make it and turn on a power head till I am ready to use it, usually within a few hours. But I want to mix it and draw from it over a 2 week period. I just read on another thread some comments about not keep a powerhead on all the time is better?  Airstone? I thought is was Origami who commented on not mixing it constantly preventing the brown buildup? 

[pizzaguy]

I put a recirculating pump on my 250 gallon container. I leave it run all the time

[pizzaguy]

My water lasts about a month at a time

[AlanM]

I do the same thing as pizzaguy.  Supposedly having a pump all the time with IO or RC causes some kind of anti-caking agent to leave a brown film on the mixing container.  Something does leave a brown hard film in mine with the pump running all the time, but it doesn't seem to hurt anything whatever it is.  I use my 35 gallons of saltwater over the course of a few weeks and mix it up from time to time.  I definitely don't use it all at once.

[Origami]

I mix mine twice a day for about 15 minutes and let it sit the rest of the day. The only exception to this is when I'm mixing it up for the first time. Then, I set it and forget it (typically for about a half hour or more - just to get stuff dissolved). HOWEVER, I will mix it for a few minutes before I use it for a water change. I'm not sure that there's any real benefit to mixing it (other than oxygenation). You really won't get any settling or stratification in the water. And, it unnecessarily consumes power.

 

Reference: "Assuming that it is made from adequately pure freshwater, mixed artificial seawater can be stored for as long as needed without continuous stirring or heating.  I keep mine for a few weeks completely unstirred after initial mixing.  It will not become anaerobic (although used tank water or natural seawater may become anaerobic due to the breakdown of organics in it, and should not be stored unaerated)." - RHF (3/2007)

[treesprite]

Great information to have. I have been keeping a powerheads in mine, because that is what I thought I was supposed to do. Now I know better!