RO/DI unit is from the AirWaterIce website. It's been successfully installed under the kitchen sink (not the most convenient placement, but since I'll be living here with my parents until I finish my bachelor's degree it'll have to do

)
Reefman13, I agree with you completely. However, I've been using RO water from the store this whole time, and I don't dose anything, so I don't think that Iodine/Copper is the problem (Granted, I have no tests for either, so it very well could be). I'm inclined to think they're afflicted with some sort of pest.
TDS Readings
Tap water: 369
Water dispensed from refrigerator: 229 (just for fun)
RO Water from store: 12
I haven't tested the RO/DI yet, but I'm presuming that it will be zero
Edit: I pulled out what appears to be one of those sundial snails that cause problems with Zoa's...I guess I'll just watch over the next several nights and pull out any little snails I might see and hope that helps the zoa's. I've got some Kent Iodine solution, and I've heard of people using Lugol's iodine as a dip treatment for Zoa's...would the Kent stuff work the same way?