Why exactly are you draining it? I used a sump with a hose attachment and vacumed the bottom of my pond with a Pool vac. Waste water went into flower bed. Then I'd clean the filter pads in a rubbermade tote using pond water and use that water to feed my rose bushes in the back yard. Check the levels and for the most part they were always spot on. And the 40 or so gallons I would pull out of the pond for the filter rinse and vacuum could be filled back in the 10 minutes that it took to clean my filter pads.
If it got really hot over the summer and no rain for a few weeks I would add an inch or two of water, but that's about it. I was at a point that I could clean and service the whole pond and filter in about 35 minutes.
What I do right now is i use a broom and sweep the gunk into the pump and it pumps it out. I also use a net to get some leaves out. I am currently trying to find me a pond vacuum! I use the water I pump out for the lawn and my moms flower garden.
Filter pads get hosed off monthly, skimmer basket cleaned 1-2X per week.
In spring/early summer, I use a small broom to sweep the bottom towards the skimmer when I feed, 2 birds.....
Spring and Fall i have a liitle more time invested to keep string algae in check and plant maintenace. Maybe a hour or two, but that is getting really picky.
In the summer I will trim the dead lilies every 3 days (10 minutes) and clean the mechanical filter every week (30 minutes). Bio filter I clean every 6 weeks (45 minutes) in the summer.
In the winter I do close to nothing. I clean the mechanical filter every 3 weeks [no freeze over here - low is 9c] (20 minutes).
At the end of the winter (Mar/Apr), I rent a pond vacuum, take out all the plants and prune them, clean the mechanical and bio filters and that generally takes me about 6 hours. But that is once yearly.