as long as its a bar tank it wont cycle,i dont think theres a time limit to for use either.i used to mix my salt in a 55 g tank sometimes the water would sit for month or longer before use.the only thing i did not like was after so long white gunk would form in the water, but i was told it was harmless and from room light.if i was to mix water like this again,i think i would use a rubbermaid trash can with lid.