I have a 40g breeder and change out 5g/wk with daily AWC with an apex DOS. I make new saltwater every week, but by the end of the week the saltwater in the AWC bucket smells a little musty. Do I need a circulation pump for a storage container this small and for no more than one week of storage? If so, what pump would you recommend for a 5g bucket? And should I run it 24/7? Any help is greatly appreciated!!!