How do you change the water in a rasa 360?

The reverse of how you filled it?

I have a lot of links below and filling a loop is included in several. I think you might consider doing a lot more research and learning as it seems you are about to dive into something you know nothing about.

i know alot about im just reasurring some things but thanks for the help!

Yeah, changing the water is pretty simple. Disconnect power, disconnect a line low in your loop and let it drain. You can blow in the other end to help force out water if you want.

6 months is a little early for most people. 9-12 is more reasonable. If you are only running distilled with a killcoil and/or some biocide you could run it indefinitely. Some guys on OCN and XtremeSystems have their loops up for 2-3 years without changing water. Most of them also don't run additives. In fact, I've had my loop running almost 2 years on distilled + biocide and some dye and I haven't had any issues. It's about time to clean my entire loop though...I need to rebuild.