Thanks Waterbear. I read this advice from you some time ago and thought, oh no, I could never do that! That said, I think I have l have gained enough knowledge on here since then to have the confidence to try this. I will top off the borates, CYA et al and then add the bleach the night before we leave. I will let you know how it goes. This will probably be a perfect opportunity to soak my carts for two weeks as well.