Howdy- But of course.
I added plumbing as you suggest right after these pictures were taken.
Everything is carefully tested for a power fail situation, as I stop the main pump once a month or so for water changes. I try not to rely on a check valve as they are not 100% fail proof, but I do have one large one in the system. If it fails, the system will draw down the main tank a few inches extra, but not drain it.
Update:
About two weeks ago I took them off line. I've upgraded my lighting to MH, and can't run just two VHOs on my ballast (have to run all four). I was getting a lot of detritus in them, and algae growth too. I moved everything back to the main tank under the MH.
I have not decided what to do with them yet- Maybe make a non-lighted rock area, or a settlement filter out of them.
Zeph