With this little DWC they are in I change the water every 7-10 days. It's usually used mostly up by then. To change it I just take the whole thing out and bring it to the bathtub which is about 5 feet away. When full it has 4 gallons, so any less and it's not Too heavy. At least for a young back. It's easy enough to put a water pump in with the cord hanging out. When you want to change it, just plug in the pump and run it to a bucket or all the way to a drain. That's one of the reasons I love the tube set up is the tank is totally separate from the roots, so I can mess around in there and not mess with the roots.