...and you aren't using the other one(s) for some time, is there a thing you should do?
Clean the pen or something like that?

Sorry for the maybe another newbee question, I just want to learn something if possible..

I wish I had Da Book here, Frank pretty much lays it out.

I flush and rinse the pen until the water runs clear. I shake the water out, being VERY careful not to let the pen or section slip out of my hand. Get it as dry as you can.

You can also put the pen nib-down in a cup full of paper towels, the will pull the water out pretty well.

Let the pen dry and store it on it's side somewhere safe.

By all means,if you're not going to be using that pen for a while,you need to expel all the ink out of the pen and then flush it out with cold water(I flush mine out with cold water several times to make sure that I have gotten all of the previous ink out). Leaving ink in the pen for an unknown amount of time allows the ink in the nib/feed/breather tube area to dry up and clog up the works.

John

And again some GREAT advice here, thanks guys...

Let us say cool or even room-temperature water. Simply avoid the hot tap. If you do happen to let the pen dry out with ink in it, repeated fills with water will generally effect a cure, too, but prophylaxis is better than remediation.

Just cleaned the few I have right now.
They are now drying on a soft cloth after I dipped then carefully with some soft toilet paper.

Thanks again for the great advice here guys.