Definately NO to the check valve, for reasons already stated...they're evil ! Not that I'd know...
Tony's got lot's 'o plans ! I like the closed loop idea. Definately ugly on the first idea. The last one sounded like a good one too. I'd certainly recomend doing some friction fit test runs if your going with slip fittings, just in case Tony ain't so brilliant either
. The siphon break holes will have water forced out so don't point them to the ceiling...that airline feeding back to the water surface has got trouble written all over it...
"I thought I was brilliant..." that sounds like te beginning of my posts...