Quick Salt question

[Pufferoni]

I have a 10g rubbermaid tub I use for my brackish water changes. After my weekly change I fill it up with treated tap water, add marine salt. It has a filter circulating water and heater maintaining 80' F.

I have noticed a black residue on the bottom, like dirt. Is this just the "stuff" in the salt or is it something else. Should I stir it up before a WC so it goes in the tank or not.

Thanks

[Pufferpunk]

I always clean out my bucket after a few mixings.

See: http://www.reefkeeping.com/issues/2005-07/rhf/index.php

[Pufferoni]

Wow great Article. Thanks PP.

[Pufferpunk]

[Nick]

I empty tank water into the same bucket I mix in, so it gets washed out when I rinse the residue out.