works great, provided your empty the water into something that is lower than the tank level, if your sink is higher, you’d have to pump pretty much all the water out. I usually just pump it out the window into the garden, once you get a flow, it pretty much drains itself, but pump the bulb to get a good suction on the pebbles to clean them, than let the water flow by itself out. I had to pump it into the sink yesterday due to a winter storm, the flow did not go into the sink, had to keep pumping the bulb, arms are quite tired pumping every drop of water out of the tank. Will pump it into a bucket next time.

I got this as a gift for my father-in-law since the mini version worked well for me. He is very happy with it as it makes cleaning his tank so much easier.