Keeping Freshly Mixed Saltwater in Basin for Long Time

[Siapin]

I have a 20g nano, and I do about 3 gallon change per week. I'd like to buy a trash barrel, and mix about 40 gallons to have ready for whenever I need, rather than mix new salt every week. I would have a lid covering it whenever I'm not using it. But 40 gallons would take me 3-4 months to use up completely.

How long can I keep mixed salt water in closed container before worrying about nutrient depletion? Do nutrients deplete, or stay same, since there is no bioload in the container?

 

[Randy Holmes-Farley]

Nutrients? There should be little to no nutrients such as nitrate and phosphate in raw artificial seawater, and it is fine, IMO, to store it for a few months in a plastic trash can. Just aerate it before use.

The same is not true of used tank water or natural seawater, where the breakdown of organics can make it become anaerobic and potentially produce hydrogen sulfide which is toxic.

 

[Siapin]

How do I go about aerating? Do I need an air pump? Can I use a little rio water pump? Or just swish the water around?

 

[Randy Holmes-Farley]

For stored artificial seawater, an airstone or just a powerhead with the lid open for 24 h or more should suffice.