Re: Cleaning
As part of my weekly WC's, I've been vacuuming gravel in halves - one side one week, the other the next. I dig into the gravel a bit to suck out the waste, excess food.
To clean algae this weekend, I used a scrubbing wand for the first time. It was not new out of the package and is typically kept in the cabinet beneath the tank. It's possible that introduced something vicious to the tank, but 3 of the 4 deaths occurred before this cleaning. I also removed and replaced all the faux plants (this is not a planted tank) to remove algae build up on those.