I'm somewhat removed, but I'd like to comment just because I really like this project and I like how you are all running it. If I lived closer I'd be pitching in.
There is probably a reason, so forgive me, but I don't understand why the two tanks are separate. From an outsider's opinion, there is added complication surrounding the seahorse tank.
Why not plumb that into the main system, and have the tank drilled and make it so there are fewer worries, I imagine that there aren't people there every moment so it should be as reliable as possible, as fool proof, (really idiot proof) so that way in a pinch anyone can come and fix an issue that arises, or be explained how to do so over the phone.