Brandon is correct Roberto. To my knowledge, traditional high pressure pumps are not submersible. I have however, experimented with Magnetically driven pumps in the past (high flow, low pressure) and have gotten them to work out very well with misting systems. This was a few years back though and I have since moved on to the aforementioned pumps. As another note, any ol' timer will not work. Even with the digitals, the minimum on time is 60s--far too long for most setups. You'll need to invest in a repeat cycle timer (usually minimum on time of 5s) but they are terribly expensive ($75+). I am designing a commercial misting system right now that will make automatic spraying systems affordable (relatively) for everyone. Best of luck on yours!
-Harold