Workout

Warm-up (500)
400 swim
100 kick

Set (600) 
8 x 75 on 1:15 
...25 drill/50 build 

Set (2100)
3 rounds
4 x 50 Fast
... :45, :40, :35 
2 x 100 on 1:30
...steady recovery 
2 x 150 Fast
...2:00, 2:10, 2:20
   

Cool-down (200)
200 easy