Yeah, I guess you'd have to plumb an emergency overflow if you went with an automated valve (one nice thing about the toilet flapper valves is they have that "feature" already). The thing that turned me off the automated valve idea, when I looked into it, was the cost ... "ouch" doesn't begin to cover it. I guess there are sprinkler valves but I'm not sure how big they get, or how well they'd stand up to saltwater .. the ones I looked at, at Home Depot, had metal springs and so on, so I don't think they'd be suitable.
Anyhow I'm real excited to see this project progress, I'll be watching this for sure!
