Hello Shani Rosen,
This seems to be of help, also:
Thank you for this question; I have been approached about aqua classes.
Natalie aka NAPS 2 B Fit.
when I taught aqua, I did timed interval training, in other words one move with modifications and directional changes and higher intensity) for 90 or 120 seconds, then a brief rest of 30 seconds, and repeat. I started the class with a five to 8 minute warm-up and ended with a 5 minute cool-down / stretch.
I never did any counting because the class participants preferred to go at their own pace, and that was fine with me.