How do you do water changes on tanks that are <10 gallons? I just set up a new 3-3.5 gallon tank last night and was wondering how I am going to do water changes on it, since I have never had a tank that small before other than my 2 gallon (but for the 2 gallon I just use a plastic cup to remove the water). Do they make siphons small enough to use on smaller tanks, or do you just have to do everything completely manually?