In order to effectively pool run you need to be in the deep end where you cannot touch the bottom. It is very similar to treading water, but you are going through the motions of running. We pool run 30 minutes the first night, and then another 30 minutes the next day along with swimming laps. It definitely is not running, but it gave me a great workout.
Pool running is great because it allows you to keep your aerobic fitness without the impact of running.
Since I am not a pool running expert, read THIS ARTICLE!