It explains the mechanism well enough. Learned this formula P=ÃÂgh long time ago but is the first time to see it actually is doing any good for us.
The unit doesn't appear to be quiet energy consuming as it works in one of the two modes: periodical monitoring (30 sec every 15 mins) and on-demand monitoring (react to ph calls). Ley! you're right. That's 12V Gel-Cell Battery.
BTW, "If vandalism is a concern, the system should perhaps be mounted on top of a tree or a high pole." A tree is the way to go!