Ornamental Grasses/Sedge help

Couple of questions, if anyone can help.
I have a few ornamental grasses, that are all doing really well - a bit too well, they are outgrowing their pots. Can anyone tell me how to split them, and when is the best time to do it?

Also, I have a lovely Juncus 'Spiralis' growing with some Equisetum. I love the contrast of the tall, poker straight Equisetum, next to the crazy curls of the Spiralis. As they are both happiest standing in water, I am putting them together into a large plastic container with no drainage (mini pond). I really wanted to add a third sedge/ornamental grass for contrast - ideally red or orange. It would need to like the same conditions (sitting in water, semi-shaded position). I fancied a Red Hook Sedge, but I'm not sure it would like so much water. Any suggestions for a third to add to this pair?