I clean out my resevoir and put in new nutrient every week.
I use Advanced nutrients, and that's what it says to do.
Each week takes different dosages of nutrient, and micro nutrients.
As far as the table, I only wash it out if it's extremely dirty.
When washing my resevoir and table, I use a tiny bit of hydrogen peroxide
and hot water.
All of the pumps and hoses get washed with plain hot water every week.
Once a month I'll wipe down the walls inside my grow room, I use Simple Green for the walls.
I don't get too crazy with the cleaning, except for the resevoir.
Once your plants are in the final stages, you won't want to disturb them as much as possible.