Troy, I'm starting see a totm curse. It seems like half the tanks we feature end up coming done right afterwards. But, then I saw you mentioned blue rams and discus, my two favorite fw fish of all time.

Agree with everyone else that surface skimming is the way to go on both the salt and fw tanks. I would definitely use some sort of cover on the fw tank to keep salt spray from entering it. When I had a fw tank next to a salt, the fw tank would always have a slightly elevated specific gravitity (1.001-1.004). Not much, but it may be a problem with the discus.

Have you thought about using a hiatt on the fw tank? If you want, I've got a spare torpedo sitting in the garage that you could use.

For anyone interested, here's pics of the aforementioned culprit.