For practice, place 5 vertical entities in a row. The top entity being the water level, the bottom four being null entities. Then do this.
(Event numbers are gonna be in vertical order (300 - top, 304 - bottom).
Code:
#0200
<KEY
<CNP0300:0000:0000<CNP0301:0191:0000<WAIXXXX
<CNP0301:0000:0000<CNP0302:0191:0000<WAIXXXX
<CNP0302:0000:0000<CNP0303:0191:0000<WAIXXXX
<CNP0303:0000:0000<CNP0304:0191:0000<WAIXXXX
<END
And the same can be done in reverse. I thought my previous explanation was easy to understand. (Technically, if you wanna do that in reverse order, you can also just do this, since the only available direction is up. But it will require testing over and over again to check the timing.)
Code:
#0201
<ANP0304:0010:0000<WAIXXXX
<CNP0304:0000:0000<CNP0300:0191:0000<END