Hi! My husband and I are new at RVing. We recently purchased a 1998 Sportsmen camper trailer and have been on 2 trips so far. Our question is, when our trailer is not being used should we leave a couple of gallons of water and chemicals in the grey and black water tanks? Or should they be drained completely after being treated with the chemicals? We go camping once a month and the rest of the time the trailer is sitting at a storage facility. Thanks in advance for your replies.