I have a small Ryobi pressure washer that does a great job of cleaning the walls of the sump.
The only time I use bleach is when the aft head area starts to smell bad. After putting a bung in the hoses where they drain into the sump, I put an ounce of bleach in a full sink, and run it down the hoses. After a couple hours, I drain it into the sump and empty the sump with the bilge pump, then run another sink full of fresh water down and drain it again. That takes care of any odor.
After 9 years my copper strap looks like new. When I bought Kristy (10 y old), the strap was corroded completely thru. I'm betting the prior owner used bleach regularly.