That link is very good. I was going to install an automatic water changer but found out I wasn't allowed to tap into my water line because I rent my apartment instead of owning my own house. For renters, since it's not possible to install an automatic water changer as described in the link above, a good solution is to buy a sink-faucet connection to a gravel siphon. I bought the Python No Spill Clean and Fill, but there are other models. I simply attach one end to the sink, stick the other end in the tank, and then turn a valve to make the water go either in or out of the tank. It's a good compromise for people who don't want to haul buckets of water around but can't install an automatic water changer. I'm very happy with it :)